After the installation of the sewer system, before proceeding to the finishing work inside and backfilling the trenches from the outside, the drainage network must be tested to make sure that the nodes, pipelines and their connections are tight. Checking the external system and the internal network is carried out in various ways, regulated by the fundamental document of the builders - SNiP. How the tightness of pipes and sewer connections is tested by spillage, filling, and other methods, and what data is entered, if necessary, in the inspection report, you will learn by reading the article.
Sewer units and systems to be tested
The entire sewerage system in each building is divided into an internal sewerage network and an external sewerage system. The internal sewer wiring includes the following nodes to be checked:
- plumbing fixtures and places of their connection with outlet pipes;
- local sections of a horizontal pipeline with pipes flowing into it from plumbing fixtures;
- sewerage risers;
- outgoing pipe.
In the outer part of the sewer system, sections of the pipeline (between cleaning, auxiliary equipment) are tested for tightness, as well as:
- operability of wells, tightness and slope of the pipeline;
- condition of treatment or storage facilities (reservoirs);
- storm sewer.
Parties involved in the verification
If we are talking about more or less large-scale construction, where several organizations take part, not counting the customer, they all test sewer systems, after which the results are documented in the corresponding inspection report.
Usually, the following are involved in checking the sewer system:
- the organization that drew up the project and is responsible for the correctness of the calculations and the selection of materials and components;
- a company that analyzed climatic and soil conditions and made recommendations on the layout of the external components of the sewer system;
- a contractor who was directly involved in the installation work related to the laying of internal and external sewer networks and is responsible for the compliance of the measures taken with the project and the existing requirements prescribed in the SNiP;
- a customer who controls the correctness of testing of outlet pipes, connections and some functional units of the sewer network inside the building and on the outer section of the sewage disposal system.
Each of the representatives of the parties participating in the tests and signing the final test report is responsible for inaccuracies and shortcomings that arose during testing of system sections, individual nodes or the entire network as a whole.
Methods for testing sections of internal sewerage
What and how is checked when checking the compliance of the internal network with the project and established standards is described in SNiP “Sewerage. Internal and external networks and structures. According to this fundamental construction document, the following parameters of the sewer system are subject to verification inside the building and then reflected in the final document (certificate of verification):
- testing network pipes for strength, and their connections for tightness;
- compliance of the location of the installed devices and elements of the outlet pipeline with the design documentation;
- correct installation of plumbing fixtures in relation to the floor surface (the distance from the floor to the upper edge of the receiver of each plumbing fixture is prescribed in the above-mentioned SNiP);
- the presence of a slope of horizontal sections of the pipe and the degree of verticality of the risers.
The test of pipes and connections for tightness in a gravity system, regardless of the material of manufacture of the pipeline and fittings, is carried out by the spill method. The essence of the technique is that part of the main pipeline (lounger) is fenced off in a certain area from the rest of the system. This is done with special plugs through the revision holes. The separated section is checked by filling with water through the nozzles of plumbing fixtures. According to SNiP, the results of the spill deserve attention if the pipeline was filled with the participation of at least ¾ (or 75%) of all devices connected in this isolated section. Testing the pipeline by the spill method is considered positive if the connections, after filling the system, did not give the slightest leak within 10-15 minutes (depending on the volume of the area filled with water).
According to the regulatory documentation, the strait, that is, the test of the sewer system by filling it with water, is informative when the air t˚ is above 5˚. If the temperature is lower, a pneumatic leak test of pipes and connections is carried out (with compressed air). The integrity of the riser is also determined by air, sometimes - the outer sections of the pipeline. Let us apply the pneumatic testing method in assessing the performance of a pressurized sewerage system, when wastewater is forced out, under pressure created by pumping equipment.
The location of the installed plumbing fixtures and its compliance with the design documentation is determined visually. The standing height of the receiver of each device, the correct connection of the toilet drain, washbasin siphons, bathroom sinks, etc. are objectively assessed and reflected in the act. Visually assess the condition of the plumbing fixtures themselves. They must be free of visible contamination and mechanical damage.
The correctness of the slope of the pipes inside and outside the building is controlled using a bubble building level. If the slope of the lounger of the internal sewerage network is allowed at least 1 cm per linear meter, then outside this figure must be increased to 2 cm per meter.
The installation position of the riser (this data is also reflected in the final act) is checked with a plumb line. A deviation from the vertical by 3˚ is allowed. A water tightness test of the riser is also carried out. The pressure in this case should be about 0.8 MPa.
Testing the sewerage system outside the building
Outdoor sections and nodes of the sewer network are in most cases carried out hydraulically (except for the mentioned situation with low air temperature). The test objects are:
- pipeline (tightness, slope);
- operability of differential and rotary wells;
- the state of storm sewers (tightness of gutters, gutters, the ability to divert a given volume of water per unit time).
The outlet sleeve is tested like an internal pipeline (flow, compressed air). In pressure sewer networks, the integrity of joints and pipes is checked under pressure. The test is considered positive if the pressure at the inlet and outlet of the system is the same, which indicates that there are no leaks.
Wells are tested by filling with water. A filled tank with hermetically sealed inlet and outlet should not form leaks, that is, the water level in the well should be constant for a certain time. Testing of other structures included in the external sewer system (cesspools, septic tanks) occurs in a similar way. The results of the leak test are reflected in the act.
Storm sewers are checked as follows:
- the drain is sealed into a common outlet pipe;
- the system is filled with water (horizontal drainage along the perimeter of the roof, vertical drains);
- the result is taken into account after 10 minutes (for metal systems) or after 20 (for plastic ones);
- a positive test result for the storm drain is entered into the inspection report if the water level has not changed, and leaks are not visually detected at the junctions of pipes and fittings.
Important! If a sealant was used when joining the storm water drainage elements, the system tests are carried out after a day from the moment the installation work is completed.
It is necessary to test the sewer system before starting finishing work inside the building and backfilling trenches and pits outside. Testing allows you to find and correct defects made during the installation of sewer pipelines and structures in time. Sewerage operation is possible if in the final document (inspection report) all tests carried out in accordance with SNiP were successful.
