Sewerage in a private house: scheme, laying depth, installation


In indi­vid­ual con­struc­tion, sew­er­age is a com­plex set of engi­neer­ing equip­ment designed for effi­cient and safe dis­pos­al of waste­water.

Its main pur­pose is to col­lect waste­water into a sin­gle high­way and trans­port it for dis­pos­al.

But it is the high-qual­i­ty prepa­ra­tion and arrange­ment of the sew­er­age sys­tem that large­ly deter­mines the com­fort in the house.

Choosing pipes

All pipes used in sew­er sys­tems are divid­ed accord­ing to the mate­r­i­al of man­u­fac­ture, the length of a sin­gle ele­ment and the diam­e­ter. The most wide­ly used pipes are made from the fol­low­ing mate­ri­als.

Cast iron

Despite the fact that cast iron pipes have almost left the build­ing mate­ri­als mar­ket, if nec­es­sary, they can still be ordered today. Their main advan­tage is high mechan­i­cal strength.allow­ing you to lay shal­low sew­er lines even under the road.

How­ev­er, a big the strength of cast iron is very unfor­tu­nate­ly com­bined with high brit­tle­ness. At the same time, cast-iron drains silt up very quick­ly, require reg­u­lar clean­ing and are of con­sid­er­able cost.

PVC (polyvinyl chloride)

Dif­fers in low cost and accept­able oper­a­tional char­ac­ter­is­tics. The main dis­ad­van­tage of PVC is its high hard­ness. As a result, pipelines made of this mate­r­i­al res­onate very strong­ly and make noise when waste water pass­es through them.

With the strength of the mate­r­i­al also leaves much to be desired. It is pos­si­ble to lay PVC sew­er­age only in high­ly com­pact­ed soil or inside a pro­tec­tive box.


Pipes made of this mate­r­i­al are dis­tin­guished by such qual­i­ties as:

pvc pipes in the basement

  • elas­tic­i­tydue to which the poly­eth­yl­ene sew­er, even after com­plete freez­ing, returns to its orig­i­nal geom­e­try and can be fur­ther oper­at­ed;
  • insen­si­tiv­i­ty to chem­i­cal reagents;
  • the pos­si­bil­i­ty of lay­ing in mov­ing soils.

Main dis­ad­van­tages:

  • soft­ens at 80 degrees, what can lead to pipe defor­ma­tion;
  • great wear dur­ing the pas­sage of abra­sive par­ti­cles.

There­fore, for sew­er­age sys­tems, the option of pipes made of cross-linked poly­eth­yl­ene is more suit­able. This mate­r­i­al is more durable and able to with­stand high tem­per­a­tures with­out defor­ma­tion and destruc­tion.


For sew­er­age in a pri­vate house, polypropy­lene is of the great­est inter­est. It has a lot of advan­tages:

  • accept­able cost;
  • excel­lent wear resis­tanceallow­ing you not to wor­ry when sol­id abra­sive par­ti­cles enter the sew­er;
  • soft­ens only at 140 degreesx, allow­ing you to drain even boil­ing water into the sew­er for as long as you like;
  • resis­tant to chem­i­cals. Only large vol­umes of con­cen­trat­ed acid can dam­age polypropy­lene pipes.

At the same time, with the exter­nal lay­ing of polypropy­lene sewage, it should be well insu­lat­ed. At tem­per­a­tures below ‑5 degrees, the pipe will lose elas­tic­i­ty and may crack.

The diam­e­ter of the pipe in a pri­vate house depends on the pur­pose of the sec­tion of the high­way:

  • 40 or 50 mm for wash­basin, kitchen sink, bath­tub and oth­er san­i­tary ware;
  • 110 mm for the toi­let, ris­ers and mains.

The increased diam­e­ter of the pipe for con­nect­ing the toi­let is nec­es­sary not only to sim­pli­fy the descent of fecal mass­es. When the tank is com­plete­ly drained through a nar­row pipe, a vac­u­um effect may occur, which is fraught with dis­rup­tion of the oper­a­tion of all siphons in the sys­tem.

sewerage scheme

what does the sewerage of a private house look like in a section

A sew­er­age scheme should be drawn up tak­ing into account such fac­torshow:

  • the expect­ed vol­ume of waste­water;
  • soil char­ac­ter­is­tics;
  • cli­mat­ic fea­tures of the area (sea­son­al tem­per­a­ture changes, rain­fall).

The sys­tem should con­sist of three main ele­ments:

  • inter­nal sew­er net­work;
  • exter­nal high­way;
  • sep­tic tank (cesspool).

Sev­er­al rules apply to the cal­cu­la­tion of sew­er sys­tems.

  1. When dis­trib­ut­ing sew­er pipes, it is nec­es­sary to min­i­mize the num­ber of inter­changesjoints and con­nec­tions.
  2. If the house has sev­er­al floors, then rooms with plumb­ing fix­tures should be locat­ed one above the oth­er. This will allow the use of com­mon ris­ers.
  3. The kitchen and bath­room are opti­mal­ly locat­ed in adja­cent roomsas close as pos­si­ble to the sew­er.

sewerage scheme

The dia­gram should show the exact loca­tion and char­ac­ter­is­tics of the fol­low­ing ele­ments:

  • sew­er pipes with an indi­ca­tion of the mate­r­i­allength and diam­e­ter;
  • turn­ing pointsbranch­es and inspec­tion hatch­es;
  • plumb­ing appli­ances;
  • ris­ers and col­lec­tors;
  • branch lineb;
  • sep­tic tank.

As a result, the scheme of the sew­er sys­tem should include the full amount of infor­ma­tion nec­es­sary for its instal­la­tion.


To install a sep­tic tank on the site, prepa­ra­tion of a pit will be required. Its dimen­sions will be deter­mined by the dimen­sions of the select­ed sep­tic tank mod­el and the char­ac­ter­is­tics of the soil. If the soil is very mobile, then the size of the pit should be increased by 25–40 cm. for each dimen­sion.

This stock will allow pour­ing a con­crete box for mechan­i­cal pro­tec­tion of the sep­tic tank. The depth of the pit should be cal­cu­lat­ed so that the neck of the installed sep­tic tank is flush with the ground lev­el.

The depth of the trench under the sew­er line should be less than 70–80 cm. This will keep it from freez­ing. In this case, the ter­rain should be tak­en into account. If the house is locat­ed much high­er than the sep­tic tank, then the trench near the foun­da­tion should be deep­er. The min­i­mum dis­tance to the foun­da­tion of the build­ing is 5 m.

septic site plan

The main pipe should be laid at a slight angle towards the sep­tic tank. For this, the opti­mal increase in the depth of the trench should be about 3 mm per 1 m. Such a slope will ensure the unhin­dered pas­sage of drains. With a small­er slope, there are con­ges­tion.

Exceed­ing the spec­i­fied slope can lead to the fact that the water will drain too quick­ly into the sep­tic tank, not hav­ing time to take fecal mat­ter with it. This is also fraught with con­ges­tion.

To make it eas­i­er to con­trol the depth of the trench, it is worth prepar­ing a wood­en beam with divi­sions in advance. Divi­sions are applied for cer­tain dis­tances from the foun­da­tion. For exam­ple, at two meters from the house, the depth should be 800, at four — 806, etc.

As you move away from home, the depth should always increase.. Its reduc­tion in any area is unac­cept­able. Even a small “hump” will lead not only to dif­fi­cul­ty in flow, but also to the appear­ance of an air lock, which will fur­ther wors­en the sit­u­a­tion.

Turns of the high­way can also impede the flow. As far as pos­si­ble, they should be avoid­ed. If you can’t do with­out a bend, you should orga­nize a turn of the max­i­mum pos­si­ble radius. At the turn­ing point, it is desir­able to arrange a revi­sion well.

Par­tic­u­lar atten­tion should be paid to the depth of the sew­er if it pass­es under a car park or road. In this case, it should be increased by sev­er­al tens of cen­time­ters.

To pre­vent the pipe from sink­ing into the ground, the bot­tom of the trench must be sealed with a sand cush­ion. The thick­ness of the pil­low is 10–15 cm.

For medi­um and cold cli­mat­ic zones, the sew­er line must be insu­lat­ed. As a heater, polyurethane foam or expand­ed poly­styrene sheets with a shield­ing lay­er of foil can be used.

Par­tic­u­lar­ly care­ful insu­la­tion is required for hatch­es in revi­sion wells and col­lec­tors. In a fair­ly mild cli­mate, insu­la­tion should be per­formed only for the upper part of the pipe.

Ele­ments of the inter­nal sew­er net­work must be reduced to a com­mon ris­er that acts as a col­lec­tor. The opti­mal place for lay­ing hor­i­zon­tal pipe sec­tions is in the floor screed. In this case, it is desir­able to give the pipe a slight slope.

The use of 90 degree elbows in sew­er sys­tems is not rec­om­mend­ed. Pipe turns are best orga­nized using sev­er­al bends at 30 or 45 degrees.


ventilated waste system

Effi­cient ven­ti­la­tion for the sew­er­age sys­tem in a pri­vate house is nec­es­sary for sev­er­al rea­sons.

  1. This will allow the sep­tic tank to func­tion nor­mal­ly. Dur­ing the decom­po­si­tion of waste­water, gas­es are released, the excess of which can stop this process. Ven­ti­la­tion will also con­tribute to gas removal.
  2. If the sys­tem is main­tained at atmos­pher­ic pres­sure, then improve her per­for­mance. With­out ven­ti­la­tion, water ham­mer and the appear­ance of vac­u­um zones are pos­si­ble.
  3. Ven­ti­lat­ed sew­er can last longere than its her­met­ic ver­sion.

The eas­i­est way to orga­nize ven­ti­la­tion is to install a fan pipe, which is a ver­ti­cal con­tin­u­a­tion of the ris­er. The upper cut of the fan pipe is dis­played above the roof lev­el at a dis­tance of at least 70 cm. It is impos­si­ble to com­bine gen­er­al ven­ti­la­tion in the house with a fan pipe.

Prices for materials and installation

Prices for mate­ri­als for sew­er­age sys­tems depend on their mate­r­i­al of man­u­fac­ture and lin­ear dimen­sions. Rough­ly they will be as fol­lows:

  • PPR pipe for inter­nal sew­er­age with a diam­e­ter of 110 mm, length 1 m — 830 rubles;
  • the same with a diam­e­ter of 50 mm — 720 rubles;
  • revi­sion 50 mm — 1,5 dol­lars;
  • plug 50 mm — 10 rubles;
  • toi­let con­nec­tion unit 110 × 87 — 2 dol­lars;
  • PVC pipe for exter­nal sew­er­age 5 m long — 12$;
  • 300 l sep­tic tank (Eco­prom Ros­tok Mini) — 370$.

The total cost of the sys­tem will depend on the num­ber and dis­tance of plumb­ing devices, as well as the dis­tance to the sep­tic tank.

If it is planned to involve third-par­ty work­ers for the sew­er­age device, then the prices will be some­thing like this:

  • instal­la­tion of inter­nal sew­er­age — 175–620 rubles. for 1 lin­ear meter;
  • plumb­ing con­nec­tion — from 2 dol­lars;
  • instal­la­tion of an exter­nal line 100 mm — 200–3,5 dol­lars. for 1 r.m.

When doing the work on your own, the price of instal­la­tion will only be the time spent.


The top­ic of arrang­ing indi­vid­ual sew­er­age is active­ly dis­cussed on the net­work on the­mat­ic resources. Here are the most char­ac­ter­is­tic reviews from such sys­tems:

Alla Litvi­nenko, Sara­tov:

A fam­i­ly of 5 peo­ple, a year ago they installed an autonomous sewage sys­tem. Now we don’t feel smells, and we don’t see sewage either.

Ivan­na Knopa­ka, Kasi­mov:

We’ve had a sep­tic tank for six years. There are no prob­lems with sew­er­age, plus a sep­tic tank pro­vides tech­ni­cal water.

With appar­ent com­plex­i­ty, the arrange­ment of sew­er­age in a cot­tage is quite acces­si­ble to any home­own­er. Under­stand­ing the prin­ci­ples of its work and observ­ing the tech­nol­o­gy, you can even assem­ble it your­self. But if for one rea­son or anoth­er this does not work out, there is always the oppor­tu­ni­ty to seek help from spe­cial­ists..

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