Sewerage is designed to collect and discharge liquid waste of human life. Any leakage of polluted drains leads to unpleasant consequences — repulsive odors, damage to building structures, and even to the spread of dangerous infectious diseases. In order for the operation of the system to be reliable, the sealing of the joints of sewer pipes is carried out both at the stage of laying and during the maintenance of existing communications. Various technologies using sealants can prevent leaks and correct malfunctions in the functioning of drainage ways.

The sad consequences of a leaking sewer system

Why seal sewer pipes?

Leaks in pipes occur due to installation errors, as a result of wear of pipeline parts or mechanical damage associated with freezing or shock. Violation of tightness can occur due to improper design, non-observance of slope angles and docking of communications. Increased pressure occurs in the connecting nodes, which causes them to deform and, as a result, to leak.

Sealing joints between sewer pipes is carried out in order to:

  • Eliminate leakage to the external environment. Polluted effluents, falling into the ground, cause contamination of soil and water. The smell of sewage is nothing but a mixture of gases harmful to human breathing — methane, hydrogen sulfide, ammonia, released during decay of organic waste.
  • Prevent flooding of underground structures. A large amount of emissions can erode soils under foundations, fill cellars, basements or basements. The aggressive composition of sewage water causes corrosion of building materials.
Sewage washed away the base of the highway
  • Protect pipelines from external leaks. When groundwater is absorbed from the soil, sand and earth enter the system. They accumulate in the lumen of the pipes, additionally clog the sewer.
  • Extend the service life of communications. Rubber gaskets in the joints age over time, lose their elastic properties. The process is aggravated by temperature changes, alkaline or acidic reaction of wastewater. The tightness of the system is lost, dismantling and costly repairs are required.

To choose the best sealing method, take into account the type of sewer system, the material and design of the pipes. Installation must initially be carried out without errors leading to depressurization. Otherwise, the efforts to glue the joints will be wasted.

Principles of laying sewer networks

Engineering networks for wastewater disposal include internal, external and storm sewers. They are laid taking into account the requirements of SNiP 2.04.01-85. According to the rules:

  • The diameter of the pipes is selected based on the second flow rate of the liquid. In apartments, this is 30-50 mm for appliances and 110 mm for the toilet and outlets.
  • The optimal slope of the lines is 1-3.5 cm per 1 linear meter, so that the drains move freely by gravity, without stopping.
The system should be located with a slope towards a sewer riser or a common catchment point
  • The joints of the conduits are placed at an angle of 120°-135°. A sharp change in the direction of fluid movement leads to a decrease in flow rate and the formation of blockage.
  • The diameter of pipes for external sewerage is at least 150 mm, and the minimum laying depth is 0.5-0.7 m from ground level. When laying above the freezing point, the profiles are insulated.
  • For cleaning in places where the pipeline turns, revisions are arranged.
  • Drainage and storage systems must be airtight. To eliminate the risk of contamination of the aquifer, they are removed from the well at a distance of at least 15 m.

Sewerage is laid from plastic, cast iron, ceramic or asbestos pipes. Connections — socket or socket.

Important. If the laying standards are observed, blockages that provoke leaks will become a rare occurrence.

Types of pipes for drainage


The choice of method and material for sealing is directly related to the type of sewer pipe. For the installation of drainage systems in apartments and private houses, the following are most often used:

  • Cast iron pipes. They are mechanically strong, durable, resistant to corrosion. One end is formed in the form of a bell — a funnel-shaped extension that provides a quick and reliable connection.
  • Plastic. They are made of polyethylene, polyvinyl chloride, polypropylene, fiberglass. Products differ in ease, heat resistance. Service life reaches 50 years. The inner surface of polymer pipes is smooth, which reduces the deposition of suspensions. Inexpensive price and simple installation make it possible to widely use polymer products in private construction and for repairs in an apartment.
Plumbing polymer products for pipeline installation

Ceramic, asbestos or concrete structures are used much less frequently. They are difficult to transport and assemble due to their large weight, and in some qualities they are inferior to analogues made of cast iron or polymers.

Types of sealants used and the rules for their application

The construction industry produces sealing materials designed to seal the joints of sewer pipes. It:

  • Sealing self-adhesive tapes. Strips 3-15 cm wide are made from bitumen or rubber. They can be reinforced with fiberglass, covered with a protective layer of aluminum foil. They are used to reinforce coupling joints, tie-in points or sealing cracks in communications.
Self-adhesive tape
  • polymer sealants. Viscous formulations of silicone rubber, acrylic or polyurethane cure at room temperature. They have thermal and water resistance, good adhesion to the pipe material. Acidic, vinegar-smelling substances are not recommended for working with metal, as they cause corrosion. More expensive neutrals are safer in this regard.
  • Portland cement. Clinker, calcium silicate and gypsum powder hardens quickly when combined with water. To increase elasticity, modifiers are added to the mass. It is applied to sealing of designs from cast iron.
  • Sulfur technical. Inexpensive material is produced in the form of powder or lumps. It is crushed and mixed with finely ground kaolin, heated to a temperature of 150°C. In molten form, it is poured into the socket of cast-iron pipes.
Sulfur technical granulated
  • bituminous sealants. Compositions with additives of rubber or polymers are applied hot or cold. They have high elasticity, water resistance, but become brittle at temperatures below -35°C.
  • Thiokol sealants. Heat-resistant, elastic and durable compositions are very unpretentious, have high adhesion to plastic, metal or concrete. Suitable for gluing joints of pipes made of various materials. The base of the adhesive is mixed before work with a hardener and a vulcanization accelerator.

Sealing tapes are designed to process joints from the outside. Remove the protective film, slightly stretching, apply overlapping layers. The pipe is wrapped above and below the joint by 15-20 cm. The surface is preliminarily cleaned of dirt and dust to ensure a snug fit of the strip.

Paste bituminous, polyurethane or silicone sealants are applied to the inner edge of the socket, connected to another part, left until completely cured. Most often, such compositions are used when assembling the joint of cast-iron and plastic pipes. The viscous layer ensures the tightness of the interface, compensates for the different degree of temperature deformations of the two materials.

PVC sewer pipe sealing


Installation of sewerage systems from PVC pipes consists of simple operations — the end of one element is inserted into the socket of another. Rubber o-ring ensures a tight connection. Over time, the material of the ring ages, and if the joint is under even a slight deforming stress, a leak occurs.

There are two ways to troubleshoot:

  1. Dismantling of the structure with replacement of the gasket and subsequent assembly of the site.
  2. Sealing a leaking joint with sealant without dismantling.

In the first case, a viscous sealant is used, in the second, a self-adhesive tape.

Assembling a system of PVC pipes with sealant

PVC sewer pipes are sealed in the following sequence:

  1. Clean the surfaces to be joined from dust with a cloth moistened with a degreaser.
  2. A thin layer of adhesive is applied to the inside of the socket and the outer end of the pipe to be connected.
  3. Insert the element without effort, slightly pressing.
  4. Hold the link for a few seconds until the composition dries.

Remove residual sealant with a tissue. Allow the adhesive to fully harden for 5-15 minutes.

Installation of sewer pipes using silicone sealant

Sealing PVC pipes without dismantling

To repair the joint without dismantling, free the site for free access. Use sealing tape, such as self-curing silicone repair tape.

Work is carried out according to the scheme:

  1. The tape is stretched to increase the length by 3 times.
  2. Wrap the damaged area with an overlap of up to 50% of the strip width.
  3. Lay several layers as tightly as possible.
Seal joints with self-adhesive tape

Important. The repair tape is convenient because it seals even wet, uneven or greasy surfaces. Silicone rubber vulcanizes within seconds.

Sealing cast iron structures

To seal the joints of cast-iron pipes with their own hands, they use tarred tow made of linen or jute fiber. The work is carried out according to the algorithm:

  1. Strands are wound on the end of the pipe.
  2. The structure is inserted into the socket, the fiber is compacted with a special tool — chasing.
  3. Fill the voids with a solution of Portland cement in a ratio of 9: 1 or fill with a viscous sealant.

Tow fill the joint at 2/3 of the height. When wet, the strands swell, taking up all the free space. You can use a mixture of dry asbestos fiber and cement in a ratio of 1:2. Before use, the ingredients are mixed with water.

Caulking joints of cast-iron pipes with tow and filling with polymer sealant

Sealing concrete rings


So that sewer septic tanks do not become a source of environmental pollution, it is necessary to carry out a thorough waterproofing of concrete rings. Various sealing methods are used:

  • plastering the inner surface with moisture-resistant compounds;
  • spraying on the outside of an elastic film using a special apparatus;
  • coating with cold or hot mastics;
  • pasting with rolled materials;
  • impregnation with penetrating solutions;
  • sealing seams with bentonite expanding clay, bituminous pastes.
Coating waterproofing of wells

A good effect is the treatment of rings with bituminous mastics and additional protection with a clay lock. The clay around the septic tank is covered in layers, compacted with a manual rammer.

Expert advice and possible difficulties

When laying and repairing the sewer system, professional plumbers recommend:

  • Rigidly fix the structures during installation using clamps.
  • Do not increase the slope of the pipe above 15%. If the angle is steeper, the water will not have time to wash away the waste that has settled on the walls.
  • Cracks in the cast-iron pipe should be sealed with a bandage soaked in cement mortar and a clamp.
  • If the system does not provide an angle of inclination for free flow, use special superchargers for sewage.
  • Regularly inspect drainage lines.

Assembling the sewer system in compliance with the norms, sealing critical joints and careful operation will help the structure last for a long time.


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