CU

YAH

OG

A CO

UN

TY BO

ARD O

F HEA

LTH5550 Venture D

riveParm

a, Ohio 44130

Tel:216.201.2020

Fax:216.676.1317

ww

w.C

CBH

.net

Hom

eow

ner’s

Guid

e toH

OU

SEHO

LD SEW

AG

ETREATM

ENT SYSTEM

S

Sew

ag

e S

yste

m M

ain

ten

an

ce R

eco

rdD

ate o

f Clea

nin

g,

Service or In

spectio

nM

ain

tenance C

ontra

ctor / Telep

hone N

um

ber

The printing of this document w

as funded by the Lake Erie Protection Fund.

CU

YA

HO

GA

CO

UN

TY B

OA

RD

OF H

EALTH

5550 Ve

ntu

re D

rive • P

arm

a, O

hio

44130P

ho

ne

: 216-201-2001 • Fax: 216-676-1317

ww

w.C

CB

H.n

et

Water Q

uality

Pro

gra

mW

ater Q

uality

Pro

gra

mYo

ur Sew

age Sy

stem IS YO

UR RESPO

NSIBILITY

Your Sew

age Sy

stem IS YO

UR RESPO

NSIBILITY

HO

MEO

WN

ER’S GU

IDE TO

HO

USEH

OLD

SEWA

GE TREATM

ENT SYSTEM

S

Did

yo

u k

no

w that as a hom

eowner you’re responsible for m

aintaining your sewage

system? D

id you know that m

aintaining your sewage system

protects your investment in your hom

e? Did you

know that you should periodically inspect your system

and pump out your septic tank? If properly designed,

constructed and maintained, your sew

age system can provide long-term

, effective treatment of household

wastew

ater. If your sewage system

isn’t maintained, you m

ight need to replace it, costing you thousands ofdollars. A

malfunctioning system

can contaminate both groundw

ater that might be a source of drinking w

ateras w

ell as surface water. A

nd if you sell your home, your sew

age system m

ust be in good working order.

This guide will help you care for your sew

age system. It w

ill help you understand how your system

works and

what steps you can take as a hom

eowner to ensure your system

will w

ork properly. To help you learn more,

consult the resources that are listed throughout this booklet. A helpful checklist is also included at the end of

the booklet to help you keep track of your sewage system

maintenance.

·D

o n

ot build anything over or w

ithin ten feet of any partof your sew

age system.

·D

o n

ot allow

anyone to drive heavy vehicles like cars ortrucks over any portion of the system

. Pipes and tanksm

ay be damaged or crushed. The soil in the filtration or

leaching field may be com

pacted, which w

ould minim

izeits ability to filter and absorb sew

age.

·D

o n

ot plant any shallow

rooted trees or shrubs, likew

illows or soft m

aples, near any portion of the system.

Their roots will grow

and travel laterally underground. As they

seek water, they can grow

into pipes causing blockages.

TOP TH

REE TH

ING

S YO

U C

AN

DO

TO P

RO

TECT Y

OU

R SEW

AG

E SYSTEM

HO

MEO

WN

ER’S GU

IDE TO

HO

USEH

OLD

SEWA

GE TREATM

ENT SYSTEM

S

The Cuyahoga C

ounty Board of Health conducts an extensive w

ater quality program. The focus of this

program is an overall w

atershed based approach when dealing w

ith water quality issues. A

ctivities within this

program include:

·Identifying and elim

inating public health nuisances and hazards in our surface waters

·Surveying the various w

atersheds throughout the county·

Supporting the Household Sew

age, Storm W

ater, Semi-public Sew

age, Bathing Beach and Parks&

Recreation Programs

·Educating the public on N

on-Point Source Pollution issues·

Participating in local watershed protection groups and m

eetings

Stream

Monito

ring

The Board of Health has conducted a stream

monitoring program

since the late 1980’s. This program allow

sfor the chem

ical and biological monitoring of w

ater quality in our watersheds. The inform

ation collected fromthis program

has documented the need for the Board of H

ealth’s Operation and M

aintenance Program for

Household Sew

age Treatment System

s. To date, thousands of water quality sam

ples have been collected.Likew

ise, over 50 permanent w

ater quality monitoring sites have been established w

ithin the variousw

atersheds in Cuyahoga C

ounty. This data is used to obtain general baseline conditions and to identifyproblem

areas potentially being impacted by sources of w

ater pollution.

The Board of Health also em

ploys college interns over the summ

er months to perform

various studies onspecific sub-w

atersheds. These studies enable college students with an interest in environm

ental health theopportunity to receive real w

ork experience by performing

biological and chemical m

onitoring of surface waters. If

you would like m

ore information about this program

or areinterested in becom

ing an intern, please contact the Boardof H

ealth.

Stream

Surveys

Intensive surveys are performed on specific w

atersheds.Survey m

ethods include:·

Bacteriological and chemical analysis

·M

acroinvertebrate sampling

·Q

ualitative Habitat Evaluation Index (Q

HEI) analysis

·H

eadwater H

abitat Evaluation Index (HH

EI) analysis

How

does m

y sew

age sy

stem w

ork

?H

ow

does m

y sew

age sy

stem w

ork

?O

pera

tion a

nd M

ain

tenance P

rogra

mO

pera

tion a

nd M

ain

tenance P

rogra

m

HO

MEO

WN

ER’S GU

IDE TO

HO

USEH

OLD

SEWA

GE TREATM

ENT SYSTEM

S

Pipe from

the home

All of your household w

astewater flow

s through your plumbing and exits your hom

e through a pipeto the septic tank. The contents of this sew

er pipe should include the wastew

ater from all of the drains

inside the home - sinks, toilets, show

ers, utility tubs, etc. Stormw

ater or groundwater that does not

need to be treated by the sewage system

should not enter this pipe. Drainage from

downspouts, sum

ppum

ps, etc. will send too m

uch water to the system

and possibly shorten its lifespan.

Septic ta

nkThe septic tank perform

s the first step of the wastew

ater treatment process. The septic tank is a solid

watertight tank designed specifically to accept all w

astewater from

the home. Som

e installations may

have one tank or two tanks in series. A

ll tanks should feature inlet and outlet baffles, along with an

access manhole for cleaning.

The inlet baffle ensures that entering wastew

ater mixes w

ith the liquid contents of the tank to beginbacterial breakdow

n of organic materials and separation of solids. The inlet baffle also prevents the

floating scum layer from

floating back and clogging the inlet pipe.

The outlet baffle ensures that only liquid is able to leave the tank and enter the secondary treatment portion

of your system. If the scum

layer reaches the outlet pipe, the pipe would quickly becom

e plugged.

The co

nten

ts of th

e septic ta

nk

stratifies in

to th

ree layers:

·Floating Scum

Layer - soaps, greases, toilet paper, etc.·

Liquid layer - water, other liquids, and suspended solids

·Sludge - heavy organic and inorganic m

aterials settle to the bottom of the tank.

Bacteria that naturally occur in the sewage w

hich enters the tank are necessary to break down

organic materials in w

astewater. This is often referred to as prim

ary treatment. Pathogens in the w

asteare not destroyed in the septic tank. The septic tank and its bacteria prepare the w

astewater for

treatment by the rem

ainder of your system.

THECOMPONENTS

TIPTo prevent buildup, sludge and floating scum

need to berem

oved through periodic pumping of the septic tank.

County regulations require that septic tanks be pum

pedout at least once every three years. If you have alarge fam

ily you probably need to have it pumped

more often.

The access lid for your septic tank is required to be kept tograde. This allow

s the tank to be easily located, pumped,

and inspected. If your tank is not to grade, an extensionriser can be installed at the tim

e of your next cleaning.

HO

MEO

WN

ER’S GU

IDE TO

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USEH

OLD

SEWA

GE TREATM

ENT SYSTEM

S

Along w

ith requested point of sale inspections and complaint investigations, the C

uyahoga County Board of H

ealthconducts operational m

aintenance inspections of home sew

age treatment system

s throughout the health district.Since the effluent from

home sew

age systems has been identified as a m

ajor contributor to non-point sourcepollution in our w

aterways, an on-going inspection and m

aintenance program is a necessity.

Since the inception of the Operation and M

aintenance Program, m

any educational seminars have been conducted

for homeow

ners who utilize household sew

age systems. The Board of H

ealth continues to stress homeow

nereducation as the key to a successful O

peration and Maintenance Program

. Countyw

ide stream m

onitoring andsam

pling of surface water continue to assist in prioritizing areas determ

ined to be adversely impacted by pollution

sources. Many of the sew

age systems in use today are of an antiquated design and w

ere installed over 30 yearsago. Evaluation results have show

n that less than a third of these older systems are operating in a satisfactory

manner. M

ost are not capable of properly treating and disposing of the household wastew

ater generated on adaily basis. This results in several hundred gallons of partially treated effluent, or in som

e cases, raw sew

ageleaving each failing system

every day. To help identify and eliminate these sources of pollution, sew

age systemevaluations continue to be scheduled and conducted in com

munities throughout C

uyahoga County.

Work

ing with Com

munities

The Operation and M

aintenance Program encom

passes an overall water quality and w

atershed based approachin hopes of m

inimizing w

ater quality problems em

anating from failing household sew

age systems. A

s sewage

systems are evaluated in a com

munity, the data gathered is provided to local officials. This inform

ation can then beutilized to help determ

ine the most effective m

eans of eliminating pollution sources in a specific area. In m

anycircum

stances, the design and installation of a sanitary sewer is a feasible solution for elim

inating failing sewage

systems. W

here sanitary sewers are determ

ined not to be feasible, the repair or replacement of failing hom

esew

age treatment system

s will be on going.

Many m

unicipalities have completed prelim

inary studies and have determined that the installation of sanitary sew

ersin sections of their com

munities is not feasible. Topographical lim

itations, large lot sizes or frontages, and sparsepopulation in an area m

ay result in a sewer project not being practical. In these com

munities, the Board of H

ealthcontinues to collaborate w

ith homeow

ners to repair or replace failing home sew

age treatment system

s. To date,several thousand failing or im

properly working sew

age treatment system

s have either been repaired or replacedthroughout C

uyahoga County. These activities have resulted in dram

atic improvem

ent in the water quality in those

areas. In many cases, the cost to hom

eowners for the construction of a sanitary sew

er is often comparable to the cost

of replacing the existing sewage treatm

ent system. Likew

ise over 4000 systems have been elim

inated from use as a

result of the installation of sanitary sewers since the inception of the O

peration and Maintenance Program

.

The Cuyahoga C

ounty Board of Health has also developed a regional storm

water program

to assist our 55designated Phase II Storm

Water C

omm

unities within our jurisdiction, and to also assist com

munities throughout the

State of Ohio. This program

was created and expanded from

our existing Household Sew

age Operation and

Maintenance Program

and Water Q

uality Monitoring Program

s. This program allow

s the Board of Health to

provide specific functions for these comm

unities to assist them in reaching their Storm

Water M

anagement Program

Goals. These activities includes educational outreach and participation, illicit discharge detection, M

S4 inventories,dry w

eather flow surveys, w

ater quality monitoring of M

S4 outfalls and investigative activities to locate illicitsources of pollution to a com

munities M

S4 system.

What a

re OFF-LO

T and

ON

-LOT

Househ

old

Sewage Trea

tmen

t System

s?W

hat a

re OFF-LO

T and

ON

-LOT

Househ

old

Sewage Trea

tmen

t System

s?

HO

MEO

WN

ER’S GU

IDE TO

HO

USEH

OLD

SEWA

GE TREATM

ENT SYSTEM

S

There is a misconception that all H

ousehold Sewage Treatm

ent Systems are leachfields. Leachfields

function as “on-lot” systems w

here the wastew

ater flows from

the septic tank into the soil. The wastew

aterpercolates into the soil, w

hich provides final treatment by rem

oving harmful bacteria, viruses, and

nutrients. Suitable soil is necessary for successful wastew

ater treatment.

In Cuyahoga C

ounty, and much of O

hio, the soils are too severe to allow for proper percolation into

the ground. The soils will not accept these volum

es of water and can not provide the necessary treatm

ent.For this reason, the m

ajority of systems used in the past in this area are “off-lot” sew

age treatment

systems. These system

s are designed to discharge the treated effluent from the sew

age system back into

the environment via a creek, storm

sewer or ditch.

Filter Bed

sA

lthough their design may have changed over the years, filter bed system

s have been installed in Cuyahoga

County for decades. Filter beds installed prior to the early 1970’s typically utilized gravel as a filtration

media. These older beds consisted of clay tile pipes laid on top of a 15 to 24 inch thick bed of large

gravel. A clay tile line w

as also placed below the gravel bed to act as a collection pipe. W

astewater from

the septic tank would drain into the top pipes, filter through the gravel and be collected in the bottom

line.This effluent w

as then discharged to the environment. M

any of these systems are still in use today.

Unfortunately, these old gravel beds did not function w

ell and did not have the ability to properly filter thesew

age prior to discharging it to a ditch, stream or storm

sewer. For this reason, approved filter sand has

been utilized as the actual filtration media in m

ore modern filter bed system

s. Perforated pipe is laid ingravel both above and below

the filter sand. The sand has a filtration capability that is far superior to thatof gravel.

Filter bed systems installed in the last few

decades typically use a splitter box, also know as a distribution

box. This box contains a flow diversion device that directs the flow

of wastew

ater to one side of the filterbed or the other. This allow

s one part of the bed to rest, while the other is in use. This m

ay help extendthe life span of your filter bed system

. The flow diverter should be sw

itched to alternate flow at least

annually. For this reason, the flow diversion box m

ust be kept to grade. If you do not know w

here it islocated, contact your septic pum

per, installer, or the Board of Health.

HO

MEO

WN

ER’S GU

IDE TO

HO

USEH

OLD

SEWA

GE TREATM

ENT SYSTEM

S

Hig

h-efficien

cy to

ilets and

show

erhea

ds

Toilet use accounts for 25 to 30 percent of household water use. D

o you know how

many gallons of w

ateryour toilet uses to em

pty the bowl? M

ost older homes have toilets w

ith 3.5 to 5-gallon reservoirs, while new

erhigh-efficiency toilets use 1.6 gallons of w

ater or less per flush. If you have problems w

ith your sewage system

being flooded with household w

ater, consider reducing the volume of w

ater in the toilet tank if you don’t havea high-efficiency m

odel. The use of high-efficiency showerheads can also dram

atically minim

ize the volume of

water the system

receives on a daily basis.

Pro

ducts n

ot to

be p

ut in

to yo

ur sew

age system

Even though sewage system

s thrive on wastew

ater, certain chemicals can harm

the delicate balance in aseptic tank and should not be run through the system

. They include:

·Paints, thinners, and solvents

·D

rain cleaners·

Motor oil, kerosene and gasoline

·Floor w

ax and chlorine bleach

Other m

aterials may not chem

ically harm the system

, but may cause a blockage or clog pipes. These item

sw

ill not break down and can not be digested by m

icroorganisms. The follow

ing materials should never be

flushed down the toilet or run dow

n the drain:

·G

rease, cooking oil and animal fat

·C

otton balls and cotton swabs

·Sanitary napkins and tam

pons·

Condom

s·

Plastics·

Coffee grounds

Garb

age d

isposa

lsElim

inating the use of a garbage disposal can reduce the amount of grease and solids entering the septic

tank and possibly clogging components of your sew

age system. A

garbage disposal grinds up kitchenscraps, suspends them

in water, and sends the

mixture to the septic tank. O

nce in the septictank, som

e of the materials are broken dow

n bybacterial action, but m

ost of the grindings flowthrough the tank and into the secondary treatm

entcom

ponent of your sewage system

. This can causefilter beds and filters in aeration units to clog.

USE W

ATER

EFFICIEN

TLY!

• Install high-efficiency toilets and showerheads

• Fill the bathtub with only as m

uch water as you need

• Turn off faucets while shaving or brushing your teeth

• Run the dishwasher and clothes w

asher only when they’re full

• Use toilets to flush sanitary w

aste only (not kitty litter, diapers, or other trash)

• Make sure all faucets are com

pletely turned off when not in use

• Maintain your plum

bing to eliminate leaks

• Install aerators in the faucets in your kitchen and bathroom

HO

W D

O I m

ain

tain

my sew

age sy

stem?

Savin

g M

oney

A key reason to m

aintain your sewage system

is to save money!

Failing septic systems are expensive to repair or replace, and poor

maintenance is often the culprit. Your system

will need routine pum

ping.Pum

ping frequently will depend on how

many people live in the

house and the size of the system. A

non-functioning sewage system

can lower your property value and could pose a legal liability.

Pro

tecting h

ealth

and th

e enviro

nm

ent

Other reasons for safe treatm

ent of sewage include preventing the spread of infection or disease and

protecting water resources. Typical pollutants in household w

astewater include nitrogen, phosphorus, and

disease-causing bacteria and viruses. If a sewage system

is working properly, it w

ill effectively remove m

ost ofthese pollutants.

With one-fourth of U

.S. homes currently using household sew

age systems, m

ore then 4 billion gallons ofw

astewater per day is dispersed below

the ground surface or into the surface waters. O

ver a million sew

agesystem

s are currently in use in the state of Ohio. Inadequately treated sew

age from these system

s can be acause of groundw

ater and surface water contam

ination. It poses a significant threat to drinking water and

human health because it can contam

inate drinking water w

ells and cause diseases and infections in peopleand anim

als. Improperly treated sew

age that contaminates nearby surface w

aters also increases the chance ofsw

imm

ers contracting a variety of infectious diseases. These range from eye and ear infections to acute

gastrointestinal illnesses and hepatitis.

Insp

ect and p

um

p freq

uen

tlyYou should have your sew

age system pum

ped once every three years. If you have an aeration system, you

should consider obtaining a service contract from the distributor of that particular system

. This maintenance

contract allows for routine inspections of all m

echanical components of your system

. For newer filter bed

systems, the beds should be alternated on an annual basis at the distribution box. This allow

s for thealternating of the beds and w

ill provide optimal life expectancy for your filter bed system

. If you do notknow

where this box is located, contact the Board of H

ealth for assistance.

Use w

ater efficien

tlyA

verage indoor water use in the typical single-fam

ily home is alm

ost 70 gallons per person per day. Leakysinks and toilets can w

aste as much as 200 gallons each day. The m

ore water a household conserves, the less

water enters the sew

age system. Efficient w

ater use can improve the operation of the sew

age system and

reduce the risk of failure.

HO

W D

O I m

ain

tain

my sew

age sy

stem?

HO

MEO

WN

ER’S GU

IDE TO

HO

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OLD

SEWA

GE TREATM

ENT SYSTEM

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Aera

tion Sy

stems

If you utilize a home aeration system

, special care is required. The motor, w

hich provides aeration to thesystem

, must operate continuously. If it does not, the oxygen required by the m

icroorganisms that thrive

in the aeration system w

ill not be sufficient and they will begin to die. These “sew

age bugs” help to breakdow

n the organic matter in the w

astewater and biologically convert it to stable substances in the form

ofgases and liquids. The aeration and m

ixing of the wastew

ater ensures that it comes in contact w

ith them

icroorganisms so thorough treatm

ent can occur.

Several aeration system designs also incorporate the use of filters to provide additional treatm

ent. Thesefilters need to be checked and cleaned on a routine basis to w

ork effectively. If these filters become

clogged, then the wastew

ater has no place to travel within that system

. This can cause a possible backup.It can also cause solids to clog the m

otor, shortening its life span. Untreated w

aste may eventually leave

the system and enter the environm

ent.

Aeration system

s have mechanical com

ponents, which w

ill also need to be serviced and eventuallyreplaced. Since m

uch of the additional care and maintenance required w

ith these systems is beyond the

expertise of the average homeow

ner, various companies have been certified by the original m

anufacturersto offer extended service contracts.

. . . ha

ve

an

ala

rm b

ox

tha

t is

situ

ate

d in

a

con

spicu

ou

s loca

tion

iny

ou

r ho

me

.

•A

n alarm w

ill typicallysound if a m

otor is notoperating or if you arehaving a backup w

ithinthe tank.

•O

nce this alarm sounds,

you should contact theservice provider w

hosenam

e appears on thealarm

box.

MO

DERN

AERATIO

N SYSTEM

S•

You should also conservew

ater usage until atechnician arrives torepair your system

.

•You can still flush yourtoilets and use w

atersparingly during this tim

e.

•Refrain from

washing

laundry or conductingother activities thatgenerate a large volum

eof w

astewater.

A b

ack

up

into

yo

ur h

om

e or p

on

din

g o

fw

astew

ater o

n y

ou

r law

n co

uld

result.

HO

MEO

WN

ER’S GU

IDE TO

HO

USEH

OLD

SEWA

GE TREATM

ENT SYSTEM

S

When sew

age systems are properly designed,

constructed, and maintained, they effectively

reduce or eliminate m

ost human health or environm

ental

threats posed by pollutants in household wastew

ater.

How

ever, they require regular maintenance or they can

fail. Sewage system

s need to be monitored to ensure that

they work properly throughout their service lives.

WH

Y SHO

ULD

I main

tain

my sew

age sy

stem?

WH

Y SHO

ULD

I main

tain

my sew

age sy

stem?

HO

MEO

WN

ER’S GU

IDE TO

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USEH

OLD

SEWA

GE TREATM

ENT SYSTEM

S

Leach

fields

The typical sewage system

installed throughout the country for decades has utilized a septic tank and aleaching tile field. By design, the sew

age flows out of the tank and into either a clay tile or perforated pipe

that is laid in trenches. The wastew

ater then drains from the pipes and enters the soil w

here it must be filtered

and absorbed. This effluent must be properly filtered so that it does not pose a threat to ground w

ater.

Leaching tile fields work w

ell in areas with w

ell drained, sandy soils. Unfortunately, m

uch of Cuyahoga

County consists of relatively poorly drained clay soils. These soils typically have little absorption capacity.

The soil permeability - the rate at w

hich water percolates into the soil - is very slow

. Poorly drained soilsare typically saturated w

ith water during w

et weather and stay w

et for long periods of time after a

heavy rain.

Leaching tile fields are designed to keep all of the effluent on lot. If your system utilizes a leachfield and is

instead discharging off lot, your system is not operating properly. Leachfields w

ill fail once the soil canno longer absorb the w

ater that is being sent there from the septic tank. O

nce this occurs, the wastew

ater will

either pond on top of the ground or find an alternative path and be discharged onto the ground at anotherlocation.

Evapotra

nsp

iratio

n Field

s (E-T)A

n evapotranspiration system, or shallow

leaching system, receives effluent from

the septic tank anddisposes of it by a com

bination of evaporation at the soil surface and transpiration to plants. There isalso dissipation into the soil, but it can be lim

ited depending on the severity of the soil structure.

The evapotranspiration system design incorporates a large leaching field preceded by an aeration system

or mounded sand filter bed. The trenches are shallow

to allow for the evaporation and transpiration of the

treated wastew

ater. The best soil available is typically near the surface, where the plant roots are located.

HO

MEO

WN

ER’S GU

IDE TO

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USEH

OLD

SEWA

GE TREATM

ENT SYSTEM

S

Mounds

A septic tank m

ound system can be utilized for treating and disposing of dom

estic wastew

ater in areasunsuitable for conventional septic tank soil absorption system

s. Mounds are pressure-dosed sand filters

placed above, and discharging directly to, the natural soil. Their main purpose is to provide additional

treatment to the w

astewater before it enters the natural environm

ent. Mound system

s are designed toovercom

e site restrictions such as:

·Soils that have a very slow

or extremely rapid perm

eability·

Shallow soil cover over creviced or porous bedrock

·A

high water table.

The three components of a m

ound system are a pretreatm

ent unit(s), dosing chamber, and the elevated

mound. The pretreatm

ent unit is usually a septic tank, which rem

oves solids from the w

astewater. A

naeration system

may also be utilized to im

prove the quality of wastew

ater reaching the mound. The dosing

chamber follow

s the septic tank and contains a pump, w

hich uses pressure to evenly distribute the wastew

aterover the infiltration surface of the m

ound. The mound is m

ade up of a soil cover that can support vegetation.Below

the soil is a fabric-covered coarse gravel aggregate in which a netw

ork of small diam

eter perforatedpipe is placed. The netw

ork of perforated pipe is designed to distribute the effluent evenly through the gravel.H

ere it trickles down to the sand m

edia and hence, into the plowed basal area (natural soil). Treatm

entoccurs through physical, biological, and chem

ical means as the w

astewater filters dow

n through the sandand the natural soil.

Drip

Irrigatio

nIn a drip irrigation system

the wastew

aterleaves the pretreatm

ent unit and is pumped to a

series of small diam

eter distribution piping.Several ounces of w

astewater leave the piping

through many em

itter openings spaced evenlythroughout the system

. This allows for frequent,

low pressure applications of the treated

wastew

ater to the top layer of the soil, which is

the most biologically active zone. This system

can be utilized to overcome a num

ber of sitelim

itations and can potentially allow som

edifficult lots to be developed.