How to properly drain water from a bath – 5 ways

8 min

The bathhouse is a place that often comes into contact with water. Moreover, this happens both from the outside and from the inside. And it is not enough to protect wooden walls with a waterproof coating – it is necessary to organize a high-quality drain in order to avoid frequent repairs of the foundation, damage to the bath with a pathogenic fungus and rotting wood.


Water is drained from the washing room directly to the drain tank or to the place designated for the drain. The options for organizing the water intake system can be quite different depending on the conditions in which the bathhouse was built and on the type of drain.

First you need to know the answers to several important questions regarding the construction conditions of the branch:

  1. Where will the drain be located and how much area should be allocated for it?
  2. What type of soil on your site will the bathhouse be located on?
  3. Is it possible to connect to the central sewerage system?
  4. What budget are you counting on?
  5. Will you build the drain yourself or will you use hired labor?


The longevity of the construction and the quality of the bath procedures themselves depend on the correct organization of drainage communications. Even if the volume of effluent is small, you should not hope for the soil to absorb all the liquid: the remaining water will still spoil the foundation and the soil itself, which can cause the structure to shrink. The only case when the drain may not be necessary is if the bath itself is not used more than once a month by a small number of people (2-3 people). Here you can use the so-called leaked floor, with wide planks. In all other cases, this is the first thing to plan after laying the foundation. Therefore, it is very useful to know the various ways of organizing a drain for a bath, even if you do not make it yourself, but order from a construction company.

Autonomous sewerage system with a settling well

The first and most time-consuming method is a filtering sump based on an autonomous sewage system. Here the system consists of two tanks, preferably made of plastic. The first tank filters wastewater from coarse particles with a simple mesh filter fitted in the tank. The second tank carries out the second stage of wastewater treatment before sending them to the waste pit. But for any drainage option with sewerage, a special floor construction in the bath is required.


The whole point of such a floor is to tilt towards the center of the room even at the initial stage of construction. A fitting is mounted in the center of the floor, which is flush with the floor connector, tightly sealed around the installation site. The funnel of the fitting is selected within 5 cm, with slight deviations. Sewers from all rooms, if there are several, are connected by a splitter. But it is worth knowing that the construction of a cesspool is advisable only in the case of deep groundwater, at least 4-5 m deep. Otherwise, your pit will be flooded all year round and the smells of putrefactive bacteria from it will haunt until each subsequent cleaning. If the conditions for the waste pit are favorable, then the second point in calculating the flow will be to determine the volume of the pit according to several criteria: the number of people in the bath, the frequency of use and water consumption.

Further, when the drainage project is ready, the location of the pit is calculated: it should be no further than 2 meters from the bath. If you place the drain too close, then there will be a possibility of water penetration into the foundation. If it is too far away, it will not be possible to make a sufficient slope for water to drain naturally.


When laying the foundation, you are most likely already familiar with the type of soil on the site and its properties. When creating a drainage pit, it is important to understand the physical properties of the earth, since taking this into account, accompanying measures will be selected to strengthen the pit frame. However, if the soil is not loose and does not crumble, then nothing will have to be strengthened. But excessively dense clay soil also has a drawback in the case of arranging a drain – it does not absorb well. Sometimes, on the plots, a successful combination of a fairly dense soil with good absorbing properties comes across. Then the work with the pit will be limited to the fact that you just need to dig it and arrange filtration in one of the described ways. But such conditions are very rare. Most often, the soil crumbles and you have to resort to strengthening the boundaries of the pit. For strengthening, they often use brickwork with gaps for water absorption, or wild stone (any waterproof material). The easiest option is to use a large plastic tank with many holes as the inner frame of the pit.

sliv-for-sucks-6It is also important to select the optimal size for the holes in the tank. The optimal shape for the tank in this case is a streamlined cylindrical one, since it holds the pressure generated by water in the best way. It is also necessary to provide the pit with a heavy concrete or iron ceiling.

When the tank is ready, filtration material (broken brick or crushed stone) is poured onto the bottom of the pit, and then covered with a layer of sand. Waste pipes, previously connected under the floor of the bath in one, are diverted at a slope to the pit. Moreover, the optimal slope required for rapid drainage varies within 1 cm per 1 meter of the pipeline.

Arrangement of a simple drain pit

This method of organizing the flow is easier than the first one due to the exclusion of several filtration stages. It implies all stages with the organization of the drain in the bath itself and digging a hole, but in this case only a septic tank without filters will be used. The method is used if there is no desire to bother with replacing the filtration material and it is possible to use a sewage machine to pump out wastewater.


But in this case, you should think about the approach to the pit within reach of the sleeve of the machine. The second way to clean a simplified pit system is to use special bacteria to process rotting residues in a septic tank. Its efficiency, of course, is several times lower than the complete waste removal or natural filtration, but it also takes place.

Soil filtration method

In this method, the main one is the organization of the pipe system through which the liquid will be supplied to the sewer. The system will be distributed over the entire area of ​​the site so that the water has time to pass several stages of filtration in front of the drain.


Filtration is carried out according to the drainage principle: at the first stage, a grate (at the initial section) is installed on the pipe to catch large waste. Then, in the future, the water goes through the pipe section covered with large filtering material. The last stage is a fine filter, that is, coarse sand.

Thus, the water from the effluent will be filtered throughout the entire site, simultaneously creating an additional source of irrigation. This method is suitable only in the case of a low groundwater table, since the location of the pipes should be more than 0.5 meters above the water level.

Drain pipe method

In general, this method is similar to the previous ones and differs only in the type of materials and small differences in the design of the septic tank. The longer pipe length is important here. At the same time, it is important to mount the pipe itself even at the stage of pouring the foundation with a slope towards the area for the construction of a sump.


The sump is made on the basis of concrete rings that make up the walls of the pit. The bottom, in turn, should not overlap with anything for better absorption of waste. The pipe is laid without corners and bends, and the pipe diameter is taken as the maximum possible among the sewer pipes for domestic wastewater. When installing the pipe, it is important to insulate it, since when the soil freezes, the water in the pipe can freeze and deform the plastic, at best.

Horizontal filter pad method

This method is suitable only for a seasonal bath, in which the water consumption is so low that there is simply no point in making a sump. It consists in the following: at a distance of 2-3 meters from the basement of the bath, a trench is dug 1 m long and 1 m deep, no more than 50 cm wide.


Drainage material (crushed stone, broken brick, expanded clay or slag from coal combustion) is placed at the bottom of the trench, and covered with a small layer of sand. After that, a drain pipe is laid on the bottom, taken away from the bath. The pit will be designed for a small amount of waste, no more than 100 liters. Therefore, it is worth thinking carefully before choosing this option.

Basic tips for creating a drain for a bath

In the event that there is at least some opportunity to connect your drainage system to the central sewerage system, then this is the most optimal and most effective option for organizing wastewater. If the site is located in an unsuitable area for this, then you have to carefully study the features of the soil, the slope of the site, internal communications, the presence and level of groundwater, correctly calculate the materials and energy costs. Often the owners of the bath are faced with a choice, a septic tank or a well? Both options have their pros and cons. For arranging a well, for example, it will take more time than installing a septic tank. But the right well ensures the best water filtration and virtually eliminates unpleasant odors. The septic tank is more suitable for frequent use of the bath, as it provides faster water absorption. In financial terms, the organization of the septic tank and the well are almost the same. Everything will depend on the materials used, because you can always replace, for example, an expensive plastic container with old tires, arranging them in such a way that they make up a cylindrical container.


The gutter, which was described in the last, fifth method, is permissible only in the case of a small volume of water and the absence of cultivated plants on the site. Otherwise, they will simply be poisoned by the detergents coming from the effluent, although the water will be filtered to some extent. Nevertheless, this is the cheapest and fastest way to organize a drain.

In general, despite the seeming ease in performing the task of organizing the drain, it is not so easy to calculate all communications correctly. Therefore, if you have no experience in construction, it is better to hire a team of builders – today this service is not too expensive.

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Passionate about DIY for over 10 years and all the new tools, I give you through this blog all my advice, tips, tests in all areas: carpentry, electricity, masonry, gardening, home automation ...


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