Rainstream storage, filtration and re-use of rainwater

Rainstream from Polypipe WMS offers a range of highly effective solutions for the

storage, filtration and re-use of rainwater. All products have been developed to

focus solely on the UK market and are manufactured to offer the most cost

effective solution to maximising the re-use of rainwater in the UK. Polypipe WMS

applies unrivalled technical knowledge and expertise to design and commission

applications for domestic, commercial and public sector developments.

Polypipe WMS are committed to designing solutions calculated to UK rainfall and

weather patterns. We have a clear knowledge of the environmental issues and UK

government legislation surrounding rainwater harvesting through our involvement

with the UK Rainwater Harvesting Association and British Water.

Why harvest rainwater?

• Population growth and rising consumption

is increasing the demand for water

• Climate change is creating pressure

to conserve water

• Legislation is enforcing the need

to conserve water

• Higher water charges and water

metering are predicted

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Products and Solutions 2C

Page

Climate change and water demand 2C 58

Legislation and standards 2C 59

Rainstream the complete system 2C 60 - 61

Rainstream Commercial 2C 62 - 63

Rainstream Home XL 2C 64 - 65

Tanks, filters and disinfectants 2C 66 - 67

Additional and bespoke options 2C 68 - 69

Pumps and controls 2C 70

Education 2C 71

Case Studies 2C 72 - 73

Products and Solutions Rainstream Contents

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20%

80%

2,600 Litres per day

With average UK annual temperatures predicted

to rise by up to 3.5°C over the next 70 years, climate

change is already driving the need for innovative

solutions to the management of rainfall and surface

water. Changing rainfall patterns are likely to lead to

wetter winters and drier summers, sea levels are

expected to rise and extreme weather events look set

to become far more commonplace. The summer of

2007 gave a clear indication of the consequences that

these sorts of changes can bring when 57,000 UK homes

were affected by surface water flooding which caused

£3 billion of damage.

With so many homes and commercial developments,

plus much of our major road network in the UK

currently facing a real risk of surface water flooding,

now is the time to take action.

Normal range

Above average

Substantially above average

Very wet

Normal range

Above average

Substantially above average

Very wet

Average rainfall increase 2008 figures

Climate change and water demand

The average person in England and Wales now uses

150 litres of water every day - almost 50% more than

25 years ago. Washing and toilet flushing account for

much of this figure, with drinking, cooking, car washing

and garden watering also playing large parts. Yet while

continental countries such as Italy and Spain enjoy water

supply capacities of on average 2,785 m³ per person, per

year, England and Wales has a surprisingly low capacity of

just 1,334 m³ per person. The high population densities in

areas such as South East England mean that there is even

less water available to each person in these regions.

Rainwater re-use solutions offer a way to address this

increasingly important issue by collecting and recycling

rainwater, rather than simply allowing it to drain away.

This not only reduces the demand for mains water for

toilet flushing, laundry, vehicle washing and irrigation

purposes, but also eases the potential for flooding which

can be created when rainwater deposited by extreme

storms is simply left to run to ground.

On average a non-domestic building uses approximately

2,600 litres a day, with up to 80% of the water delivered

for non-potable applications such as toilet flushing. Much

of this could be provided by harvested rainwater.

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Products and Solutions 2C

Legislation and standards

Growing public awareness of water issues has helped create

a large body of legislation and standards. Polypipe WMS is

committed to helping customers understand these issues

and comply with all the necessary requirements. As an

essential component of effective SUDS solutions, rainwater

re-use plays a central part in this process and can help meet

the requirements of PPS25, Building Regulations Part H, the

Code for Sustainable Homes and many other recognised

standards. Rainwater re-use can also help achieve the aims

of the Wildlife and Countryside Link’s Blueprint for Water

document, which offers a timetable for achieving a

sustainable standard of water by 2015. It complements the

EU’s Water Framework Directive by aiming to reduce

consumption by 20% - something which rainwater re-use

can often achieve.

Future water strategy

This document explains how the Government wants the

water industry to operate by the year 2030. It focuses on

such issues as reducing water consumption from 150 litres

per day to 130 litres per day and improving water supply by

building more reservoirs and issuing fewer abstraction

licenses. The quality of water in the natural environment is

also covered, as is the use of SUDS measures to improve

surface water drainage, the wider use of water metering in

water stressed areas and the need for better planning to

reduce the risk of flooding from rivers and rising sea levels.

For more information visit www.official-documents.gov.uk

Planning Policy Statement (PPS25)

This sets out Government policy on flood risks associated

with development. It aims to make flooding a central

consideration of the planning process, so that only

appropriate development is undertaken in areas at risk,

with that risk limited as far as possible.

For more information visit www.communities.gov.uk

The Code for Sustainable Homes

The Code is used to rate the environmental performance of

new homes in England, Wales and Northern Ireland and

compliance is mandatory. To achieve target ratings set for

2016, developers must adopt measures such as rainwater

re-use that will significantly cut water consumption.

For more information visit: www.communities.gov.uk/thecode

Making better use of a valuable resource

BS: 8515

This BSI rainwater harvesting code of practice gives

guidance on design, installation, testing and

maintenance of systems for non-potable applications.

For more information visit www.bsi-global.com

BREEAM

The Building Research Establishment Environmental

Assessment Method (BREEAM) is now recognised as

the standard measure of sustainable building

design. It addresses environmental and sustainability

issues and enables developers to prove the

environmental credentials of their buildings to

planners and clients.

For more information visit www.breeam.org

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Rainstream the complete system

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3

The flexible nature of Polypipe’s approach to

rainwater re-use means that no two Rainstream

Systems are ever the same, as each one is designed to

meet the specific requirements of an individual

application. A number of elements are common to

many types of system however and the operating

principles are largely standard throughout.

Bespoke solutions for off-site construction

The Polypipe WMS team benefits from access to

Polypipe Civils own in-house fabrications department.

Using our own products and expertise, Polypipe Civils

are able to design and fabricate any solution to meet

specific site constraints. Solutions such as bespoke leaf

filters are delivered to site pre-fabricated, reducing

installation times and labour costs on-site.

Rainwater falling onto roofs, roads and paved areas

can be collected by a variety of measures which

include guttering, channel drainage and specialised

roof drain systems.

Pre-tank filtration then removes any larger pieces of

debris such as leaves, before the collected water passes

to the storage tank.

The storage vessel is typically a large tank which can

sometimes be included within a building, surface mounted

externally or buried below the surface of the site.

Captured water is re-distributed through a second

stage filtration and pump assembly.

1

2

3

4

4

2

1

Water is supplied on demand to a number of outlets

around the property and can be used for many different

purposes including flushing toilets, watering gardens

or cleaning vehicles.

A back flow prevention device stops a backward flow

of contaminated water from the sewer and acts as

a rodent barrier.

Outlet to the sewer, soakaway or attenuation.

A sophisticated control unit monitors water levels in

various parts of the system and matches these to the

water demand at the outlets.

Third stage in-line filtration to remove finer particles

of debris before use.

An optional ultraviolet disinfection process can be

used to kill off bacteria and improve the quality of

the collected water.

5

7

10

6

9

8

10

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Water Management Solutions 2C

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Large-scale solutions from Polypipe WMS have been installed on a wide variety of projects,

from Ministry of Defence sites through to retail developments. Our team of fully-qualified

designers and engineers have the technical pedigree and manufacturing capability to design

solutions to meet any site requirements.

Key benefits of Rainstream

• Tank sizes from 1,500 to 300,000 litres

(smaller tanks are available if required)

• Leaf filter within bespoke chambers to suit

specific project

• Full technical design and support

• Complete range of additional items such as duty

standby and booster systems

• Mains water back-up

• Helps reduce your carbon footprint by lowering the

volume of water from local treatment works

• Tank system supplied with filters, pumps, valves,

component set and factory fitted inlet, calmed inlet

and outlet connections

• Bespoke design solutions offered for any site constraint

• Robust GRP tank construction

• Filter uses first flush principle (see page 69)

• Manifold system available for multiple dwellings

• Water filtered to 110 microns

• Ability to increase water capture by using

specialist filters such as Storm-X4

Assessment and advice

Polypipe WMS offers a wide range of advice and

support to help understand the solutions available for

the effective capture, storage, filtration and re-use of

rainwater. Services include - assessment, tank sizing

calculations, technical detail and system schematics.

Together these services ensure that customers receive

the most suitable and effective rainwater re-use system

for their particular application.

Rainstream commercial

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Water Management Solutions 2C

1

4

5

23

Control box

Header tank

Raised valve chamber

with AB air gap

Mains water feed

Re-used rainwater

1

2

3

4

5

1

2 3

Control unit - with AA air

gap and break tank

Mains water feed

Re-used rainwater

1

2

3

Gravity (indirect systems)

Pressure (direct systems)

Polypipe WMS are able to offer a specialist rainwater harvesting solutions for domestic

applications. The Rainstream Home XL system is ideal for both individual, on-plot rainwater

harvesting solutions and can also be used as a manifold system to feed multiple dwellings.

Where deeper burial depths are required (often characteristics of communal storage systems) this

structured wall tank is capable of withstanding water pressure up to 6m burial depths or 0.6 bar.

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Rainstream Home XL

Water Management Solutions 2C

65

The Rainstream Home XL System

The structured wall design of Rainstream Home XL

has created a system that is unique in its ability to

withstand a high water table. The key benefit of

Rainstream Home XL is that it will never need a concrete

surround in non-loaded applications, even in cases of a

high water table. All that is needed is a concrete base

which the tanks are strapped to. It provides a simple

solution to the complex problem of rising water tables

and changing weather patterns. As most systems are

installed during the summer months, when water tables

are at their lowest, the resulting winter rising water table

is often not taken into account. Some systems are not

designed to be installed within the water table and are

unable to withstand the hydrostatic pressures, resulting in

their collapse. Rainstream Home XL has been designed by

Civil Engineers to withstand these hydrostatic pressures.

Further testing has taken place proving the tank’s

capability to withstand water pressure at a burial depth of

up to 6 metres or 0.6 bar, far beyond the pressures the

tank is likely to face. The range of tank sizes offered by

Polypipe WMS has been researched and designed to meet

the exact requirements of the UK market, based on

research into the national average household water use

and the most up-to-date MET office data. Rainstream

Home XL tanks allow the homeowner to meet their exact

requirements and therefore provide the most cost-effective

and efficient solution in the market, without the need to

over-specify and incur disproportionate purchasing and

installation costs. If increased capacity is needed, Rainstream

Home XL offers a wide range of tank sizes to ensure

rainwater collection is maximised effectively. Polypipe

WMS offer both gravity-fed and pressurised systems.

Manifold System for Multiple Dwellings

A manifold system can be a highly effective and

economical way of capturing rainwater from multiple

properties. Please see page 69 for more information.

Captured rainwater

Control panelRe-used rainwater

No need for a concrete surround

Leaf filter

1

2

3

4

5

Overflow discharged through

an attenuation system

(or by infiltration)

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66

Above ground solutions

Rainstream above ground sectional tanks are also

available in capacities from 2,000 litres upwards.

Manufactured from tough pre-insulated GRP panels

they offer exceptional design flexibility and allow

tanks of different sizes and shapes to be created

to suit individual projects. These tanks are suitable

for installation inside buildings once they have

been constructed. Designed with a flat bottom for

installation onto a hard-standing surface, Rainstream

above ground one piece tanks are manufactured

from rugged Glass-Reinforced Plastic (GRP). Their

one-piece construction provides maximum strength

and robustness and they are available with capacities

ranging from 6,000 – 36,000 litres.

Below ground solutions

Rainstream tanks for below ground installation represent a practical and effective way

to accommodate a large part of the rainwater re-use system and preserve the

appearance of the site. Below ground installation protects the captured water from

fluctuating temperatures and exposure to sunlight. Manufactured from GRP they are

available in capacities that range from 1,500 – 300,000 litres. A variety of duty types are

offered which can be buried between 1 – 4 metres from the surface to accommodate

different site conditions.

Normal dutyup to 1m

Heavy dutyup to 2m

Super heavy dutyup to 4m

Tanks

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Water Management Solutions 2C

Although captured water quality can be

compromised by debris picked up from the

collection surface, it is still suitable for non-potable

purposes provided it is processed by a system that

has been correctly designed and installed. The use

of high quality components and proven system

design principles allows Polypipe WMS Rainstream

systems to meet the requirements of BS8515.

The filtration process

Water arriving at the filter is distributed evenly

across the full width of the filter cascade.

The cascade pre-cleans the water by diverting

the larger particles of debris away to the sewer.

Water then flows over the secondary filter sieve

where a special mesh allows the remaining dirt

particles to fall away to the sewer. Cleaned water

flows into the storage tank ready for re-use.

Filtration

UV radiation

Direction of flow

DNA

Disinfection

Filters and disinfectant

The disinfection process

The captured water passes through a disinfection unit

where it is exposed to a high level of ultraviolet radiation.

This alters the nucleic acid (DNA) of any viruses, bacteria,

moulds or parasites and prevents them from reproducing,

leaving the water chemically unaltered while improving

the quality. This is a particularly important process where

those people more susceptible to infection may come into

contact with the recycled water particularly the very young

or the elderly. If this is likely, or if the water may be used

in an aerosol form e.g. a vehicle wash-down area, Polypipe

WMS recommends that a risk assessment is carried out to

ascertain the need for ultraviolet disinfection.

The Rainstream range offers a wide variety of filtration

options, ranging from basic leaf filters to systems capable

of removing metals, oil, chemicals and even bacteria such as

legionella. Polypipe WMS experts are on hand to help you

choose the most appropriate option for your application.

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Polypipe WMS is committed to finding the right solutions for specific sites and is

able to offer a range of additional options to complement the standard Rainstream

system, for both residential and commercial applications.

Header tanks

Polypipe WMS can supply a range of header tanks to suit

each application. Header tanks are used in conjunction with

a gravity system and can either be connected directly to the

Rainstream tank or connected to a booster system.

Please contact the Technical Team on 01509 615100 for

further details.

Booster system

A booster system consists of a GRP storage tank and booster

pump to deliver non-potable water under pressure, around

the building, over a large distance or to a high head. The

tanks are supplied as either sectional or one-piece GRP tanks

that connect directly to the Rainstream underground tank.

Sited within the building envelope (typically in a plant room)

the tank holds sufficient capacity to ensure a constant supply

of non-potable water throughout the day. The booster pumps

are controlled via the supplied control panel and run in

sequence to increase the life of the system and give back-up

in the unlikely event of one pump failure. A booster system is

often required within a large scale development, typically

large office blocks, retail premises or schools.

Rainstream Advanced Control Unit (ACU)

Polypipe’s Rainstream ACU is the latest development in

non-domestic rainwater re-use. From designer to user the

Rainstream ACU offers a simple and effective solution for the

control of rainwater distribution. Featuring, in a single unit,

intelligent pump control combined with integral break tank

and mains water top up, the Rainstream ACU saves space in

the plant room, a separate break tank and booster set are not

required and it minimises the volume of mains water required

in dry periods.

Duty standby setsRainstream is supplied as standard with one pump.

However, in high demand applications, a duty standby set

may be required. The duty standby sets from Polypipe WMS

are positioned within the Rainstream underground storage

tanks and are typically used where there is high demand

within the building. A key benefit of the duty standby set

is the inclusion of two pumps which work in sequence.

This increases the life of the system and gives back-up in

the unlikely event of one pump failure. Available as either

pressurised or gravity systems.

Building management system (BMS) connections

The Rainstream control panel allows easy connection to

the BMS through a volt-free connection. This allows the

BMS to monitor the Rainstream system and provide an

alert in the event of a system fault.

Storm-X4

Storm-X4 is a stormwater treatment system for roof and

surface water run-off. Storm-X4 is capable of cleaning

surface water run-off from roofs, car parks and the most

polluted roads, even in heavily trafficked areas. Storm-X4

has been designed to remove heavy particles, silt and

nutrients and heavy metals such as copper, zinc and

cadmium from the surface water to provide an

environmentally sound solution which benefits the

natural watercourse and increases biodiversity.

Additional options

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Water Management Solutions 2C

Low invert drop filters

In situations where the existing drain run dictates the

invert level, low invert drop leaf filters may need to be

considered. Polypipe WMS is unique in its ability to offer

patented bespoke low invert drop leaf filters within a

prefabricated chamber. Designed to exact customer

specifications the low invert drop leaf filters and

chambers allow a minimum invert drop of only 66mm,

enabling connection to an existing drain run.

Site specific filter designs off-site construction

All leaf filters are installed within a prefabricated

chamber to exact customer requirements unless otherwise

specified. Any roof size can be catered for and we are

able to create chambers up to 2100mm in diameter,

resulting in a truly efficient and cost-effective solution.

Manifold system

A manifold system can be a highly effective and

economical way of capturing rainwater from multiple

properties to be re-used for non-potable applications.

Using one large GRP tank to serve multiple properties,

the water is fed to each individual property on demand.

Manifold systems capture rain from multiple roofs,

increasing the catchment area and reducing the

installation costs associated with multiple tank systems.

A manifold system is ideal for installation within:

• Large developments, where single

installations are unviable

• Housing Association properties

• Multiple tenant properties

• Rural developments with communal services

Integration with full SUDS solution

Polypipe manufactures a range of sustainable drainage solutions, from modular cells to pipes, for use as soakaway or

attenuation solutions. Polypipe WMS offers a fully considered and holistic approach to SUDS, focusing on system integration.

Bespoke options

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Duty standby systems

Rainstream duty standby component sets include

a double pump assembly, in-line filtration and a

control module suitable for both gravity and

pressure-fed systems. This maintains efficiency,

increases operating life and ensures continuity of

supply even in the unlikely event of one pump failing.

Advanced systems

Rainstream advanced pressure-fed systems provide

the most reliable control over the water supply and

feature a duty standby function which delivers a

constant supply of water to all outlets. The storage

tank level is constantly monitored and if necessary the

system will switch to using fresh water to maintain the

supply at the outlets.

Standard systems

The standard Rainstream control set includes a single

pump assembly, inline filtration unit and a control

module compatible with both gravity and pressure

operated systems.

In a gravity system the control unit constantly monitors

the water level in the header tank, automatically

drawing in more water from the main storage tank

if required. The storage tank is also monitored so that

fresh mains water can be imported if needed. This

ensures that the header tank always contains the

minimum water volume required for safe operation.

For a pressure system the control unit automatically

detects any demand for water and delivers a

pressurised flow to all outlets. If the storage tank

volume drops below the minimum, the control unit

draws in sufficient mains water to ensure that the

required output level is maintained.

A variety of accurate and reliable pump

and control options allow Rainstream

systems to offer a high degree of flexibility.

Control Unit

Gravity System

Pressure System

Storage TankMains Water

Header tank level sensor

Pressure sensor

Level sensor

Pump control

Inlet control

Pumps and controls

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Water Management Solutions 2C

Terms such as climate change, sustainability and global warming all now make the

news headlines on a regular basis and many people take an interest in these issues.

Polypipe WMS believes that it is essential we encourage future generations to become

more aware and actively involved.

With this in mind the company has developed a suite of teaching aids which parents and

teachers can use to engage children in water usage and other environmental issues.

Polypipe Rainstream Classroom

Polypipe Rainstream Classroom is designed for children

between the ages of 4 to 11 and offers a range of

activities which encourage them to interact with their

local environment. Created to help them discover the

answers to the questions they have, Rainstream

Classroom introduces the children to topics such as

rainwater recycling and includes access to a source of

online content and a ’moving water’ activity pack.

Polypipe Rainstream Monitor

Installing a Polypipe Rainstream Monitor pack

encourages users to monitor the water usage in their

building. Primarily intended for use with Rainstream

Classroom to monitor water use within schools,

children and teachers will have the opportunity to

collect water usage data and understand how water is

used in their school. Polypipe Rainstream Monitor is

also offered in other designs, including the option to

customise (e.g. to match a school crest or company

name) allowing companies to demonstrate a proactive

awareness of water use issues to staff and visitors.

Terry our wise rainwater harvesting owl is used

at our Rainstream Classroom sessions to help talk

about water conservation with the children.

Education

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Polypipe WMS supplies 100,000 litre rainwater harvesting solution for Bristol PFI College

A bespoke 100,000 litre Rainstream tank and leaf filter

were supplied by the Polypipe WMS team to Brislington

Enterprise College in Bristol as part of the Building Schools

for the Future PFI. Installed to cope with rainwater from

the school’s 5,000 square metre roof area, the tank will

store and filter rainwater before it is used for toilet

flushing within the new development, providing a

sustainable method of reusing rainwater. Working

alongside contractor Skanska, several alterations were

made to the standard Rainstream system to produce one of

the largest tanks of its kind, including the supply of

additional inlets on-site to suit the project requirements.

Rainstream rainwater harvesting tanks reduce mains water

consumption, providing increased cost savings on water

bills. It is calculated that the Rainstream system installed at

Brislington Enterprise College will save the Local Authority

over £10,400 per annum. The site of the new college

building is on sandstone rock, which enabled the tank to

be installed without the need for temporary support. The

tank itself was installed in a six metre deep hole and

placed into position using an 80-tonne crane to cope with

the tank’s 11m x 3.3m dimensions.

Polypipe WMS undertakes largest rainwater harvesting contract with Ministry of Defence

The Polypipe WMS team were approached by the

Ministry of Defence to supply a rainwater harvesting

solution for the largest rainwater harvesting contract

ever signed in the UK. Working in close partnership

with the main contractor, Aspire Defence, Polypipe

WMS will supply 150 of its Rainstream rainwater

harvesting tanks over the next seven years as part of

a redevelopment of various sites across the UK.

Over 42,000 litres of capacity have been installed on

the site at Tidworth, which would save the Ministry of

Defence approximately £1,500 annually through the

reduction in mains water consumption. Polypipe WMS

redesigned the original Rainstream system to fulfil the

requirements of Aspire Defence. These modifications

included a filter which was redesigned to reduce invert

loss on the existing drain run allowing for connection

with a shallow main drain. This filter was delivered to

site pre-fabricated within a chamber, bringing

increased time savings to Aspire. The flexibility of the

Rainstream system was an important factor for Aspire.

Case studies

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Water Management Solutions 2C

Earthship project

The Polypipe WMS team donated a full rainwater harvesting solution for the

recently opened Brighton Earthship Low Carbon project. Since being installed on

the project in July 2003, the four Rainstream Rainwater Harvesting tanks, each

with a 20,000 litre capacity, have harvested over 50,000 litres of rainwater per

year, giving a total mains water saving of over 150,000 litres. As an ‘off-grid’

building, materials with low embodied carbon were used in the construction of

the Earthship, with the thermal mass of the walls controlling the heating and

cooling of the building. Through the use of the Rainstream rainwater harvesting

system the Earthship project and Low Carbon Trust received a commendation

from the Environment Agency at the 2007 Water Efficiency Awards, in the

Inspiring Change and Construction & Renovation categories.

Revolutionary development uses Polypipe Rainstream

Seven Rainstream rainwater harvesting systems from Polypipe have been

installed in a ground breaking development in the heart of the mining

community in County Durham. The Close, in Houghton-le-Spring is a series of

seven detached homes on a former brownfield site, where abandoned farm

buildings were used to store machinery. This sustainable residential scheme is the

brainchild of Spring Oak Developments Ltd, a private developer at the cutting

edge of sustainable housing in the North East. Director, Bill King has a vision for

the properties to defy the conventional build for this part of the country and so

incorporated the most up to date and innovative sustainable systems and

features. He used timber frame for the buildings’ envelopes, Low E glass for the

windows as well as solar thermal panels to minimise the need for supplementary

heating systems. The Rainstream rainwater harvesting concept played a major

role in his ambition for total eco-design.

Rainstream runs rainwater recycling in Old Cantley home

A housing development by R.J. Cadman of Scunthorpe at Old Cantley near

Doncaster includes a four bedroomed home which is being built to the client’s

own specifications. Among the ‘green’ features included in the design is a system

to recycle all rainwater drained from the 311 square metres of roof area for

re-use for toilet flushing, in the washing machine and, more unusually, in the

dish washer. This was achieved through a specially designed collection and

redistribution system centred round a 7,500 litres capacity Rainstream system.

The Rainstream tank, manufactured in GRP that is totally resistant to corrosion,

was buried in the rear garden of the house with only the plate-surface of the

tubular ‘conning tower’ at lawn level to provide ready access to the internal

plumbing and electrics. The lightweight qualities of GRP proved invaluable and

eliminated the need for heavy lifting machinery. When the Rainstream Gravity

System is in operation, the drained rainwater will be piped from the gutters to

the underground storage tank, filtered and then taken up to a header tank in

the property’s loft.