Sewage pumps: types, how to choose correctly + operating features

It is not always possible to install a gravity sewer system in a private house.Then, to remove fecal waste from the cottage, it is necessary to install sewer pumps, creating a forced pumping system.

The pumping equipment market offers a wide range of units. But, you must admit, the variety of models can lead to confusion and make it difficult to choose.

We will help you resolve the issue. The article identifies the main types of sewage pumps and describes their strengths and weaknesses. In order not to make a mistake with your purchase, we suggest following a special algorithm for assessing the characteristics and decisive factors of choice.

Hydraulic pump in a forced sewer system

To choose the right pump, you need to understand all its modifications and take into account many factors.

Most often, sewers are designed so that the waste flows by gravity. But not always local septic tank or the entrance to the centralized sewer system is located below the sewer pipeline and all plumbing fixtures in the house.

Wastewater cannot rise up on its own; it has to be “forced” with a pump.

Pumping equipment is installed when, due to the topography or other features of the local area, external sewer pipes It is not possible to lay it at the required slope.

It is also possible to complete the construction or remodel the building. The configuration of internal pipelines and the volume of wastewater changes; the latter can no longer be removed from the residential building on their own.

The most popular version of a sewerage system with forced pumping of wastewater involves installing an intermediate storage tank in the basement of the cottage. As it fills to the brim, the pump turns on, pumping the liquid outside for further cleaning or removal.

But you can also install a compact pump unit that turns on only when the wastewater is drained. However, if it breaks down, the house will actually be left without a sewer system.

The task of a forced sewerage pump is to pump out domestic wastewater and stimulate its movement to the street collector, which is located above the storage or treatment plant (+)

Compared to a gravity system, the use of pressure pumps provides a number of advantages:

1. Ease of maintenance. The frequency of cleaning pipelines is reduced, since the intensive movement of wastewater contributes to their self-cleaning.
2. Variability of equipment location. Sanitary and household appliances with a connection to the sewer can already be installed anywhere without taking into account the need to form a slope towards the sewer outlet, and then the storage tank or septic tank.

According to technical regulations (SNiP number 2.04.03-85), the smallest diameter of the pipes of the external main of the pressure sewer network is accepted as 150 mm if a common drainage system is installed.

These are networks that transport stormwater together with domestic black and gray wastewater. Household gravity flow systems are constructed from pipes of a similar size.

If fecal waste is discharged separately, the diameter of the pipeline is assumed to be filled to 0.7 of its maximum height. This distance is necessary for ventilation and the ability to remove unpleasant and explosive gases.

The size of the sewer pipeline must be taken into account when choosing a pump in order to accurately select the unit for the upcoming load.

A forced system is energy dependent and costs more money than a gravity system. If the family is small, then the storage tank does not fill up immediately; it will be enough to turn on the sewer pump from time to time.

However, with large volumes of wastewater, pumping equipment must operate almost constantly. In this case, serious problems may arise if the power goes out.

Most of the costs for a sewer pump can be recovered by using cheaper and thinner pipes, as well as reducing the cost of their installation. But after installation, this equipment requires constant maintenance, which requires some money.

If you add an uninterruptible power supply to the circuit in case of a power failure, the benefit will be zero.

To install a forced sewer system for a small private house or cottage that discharges a mixture of black and gray wastewater, a fecal pump is suitable. It will cope with pumping water from a combined sewer system

If it is possible to get by with a gravity sewer option, then it is worth doing it. A pressure system with a sewage pump for viscous and contaminated liquids should only be selected as a last resort. And special attention must be paid to the competent choice of pumping equipment.

Types of pumps for pressure sewerage

The most important thing in choosing pumping equipment for pumping out sewage is to clearly separate it from drainage units and water-lifting equipment for drinking wells.

The last two options are intended exclusively for pumping clean or finely suspended water. If harder feces or debris gets inside, they will simply break.

The range of fecal pumps is quite extensive, but the entire variety of this equipment can be divided into three classes: submersible, semi-submersible and external

A special sewage pump is designed specifically for pumping sewage with all household waste that ends up in the drain from sinks, toilets, dishwashers and washing machines.

In this case, the best option is choose equipment with a chopper. Such a unit grinds all the debris before it gets inside the sewage pump.

In general, fecal pumps are used for:

• pumping sewage in sewer networks with forced current;
• pumping sludge from cesspools, septic tanks and pits of street toilets;
• pumping water out of basements and cellars;
• cleaning pipes and sewer wells from silty sediment.

A standard drainage pump will not be able to perform this work. Its impellers will quickly clog, and then the electric motor will overheat due to sharply increased loads.

Type #1: Submersible Devices

This type of pump is immersed directly into the sewer with its entire body. All elements of their design are made of stainless steel or cast iron, so that in contact with an active and aggressive environment they do not immediately fail.

A submersible sewage pump is installed at the bottom of the tank or suspended directly above it on a rope

Typically this pumping equipment operates automatically. When the tank is filled with waste, a float rises along with it, which, at a certain level of liquid, turns on the pumping unit. As soon as the container is empty, the pump is turned off by a float switch. Working “dry” is practically excluded.

Submersible models are chosen because of their high productivity and the inclusion of a chopper. The cutting mechanism of the latter grinds any large waste to a size that does not pose a threat to pumping equipment.

Almost all submersible sewer pumps come with a built-in shredder, the rotating blades of which easily cope with paper, fibrous objects and solids.

Type #2: Surface Models

Surface pumps for pumping out sewage are installed next to the collector that collects and redirects wastewater, or in the inspection well that is most convenient for its placement.

This is the so-called dry installation option. They are often also referred to as forced sewer pumping units due to the presence of several individual parts that are assembled together.

In this case, contaminated wastewater is sucked through a hose attached to the pump unit, which descends to the bottom of the storage tank. When choosing this model, you need to pay special attention to the suction depth parameters specified by the manufacturer.

Usually this is up to 8–10 m; from greater depths it simply will not be able to lift wastewater from the storage tank. In this case, you should take into account not only the height of the container, but also the distance from it to the pump.

Surface pumping equipment is easier to maintain; it can be quickly dismantled and washed in the utility room without any problems.

A low-power surface pump for use in forced sewerage is a compact unit that is simply installed next to the wastewater storage tank. Installation of more powerful models is carried out in a specially prepared place with the device securely fastened to the floor.

When installing an external pump, it is extremely important to ensure that it is protected from moisture. Unlike its submersible counterpart, it is fundamentally not designed to work in a humid environment.Its body has minimal protection from water, which can cause a short circuit if it gets inside.

The surface pump is inexpensive and easy to operate, but is quite noisy. For installation in a basement or heated utility room, it is better to take it.

However, if you need to turn on the equipment only from time to time to pump out the septic tank, then it is better to prefer the submersible option.

Type #3: Semi-submersible units

These models are a kind of intermediate option between submersible and external types of pumping equipment. Their electric motor is installed next to a container above the water, and the working chamber is immersed in the sewer. These two parts of a single installation are connected to each other by a rotating shaft.

Installation of a semi-submersible pump can be done on:

• a cushion floating on the surface of the drain;
• area next to the container;
• tank wall.

Initially, standard semi-submersible equipment comes without a chopper. It can only be installed as an additional nozzle, which complicates the maintenance of this pumping equipment and makes it more expensive.

Due to their design features, semi-submersible pumps are rarely used in domestic settings; they are more an option for industrial applications and large pumping stations

Type #4: Small units for plumbing drains

A sewer pump for a toilet or washbasin means small-sized equipment installed next to the plumbing. The wastewater from the latter first goes into a small tank, and from it it is pumped into the general sewer system.

A household sewage pump is a direct analogue of the pump in a washing machine, only it is installed for toilets, bathtubs and sinks (+)

Such equipment is quite expensive, but it allows you to install plumbing in any convenient place. When filling a sanitary tank, the pump will pump out sewage into the riser, even if the outlet to it is inclined upward.

Usually, toilet pumps with grinder require virtually no maintenance. Structurally, they include self-cleaning of the storage tank. And to prevent the appearance of unpleasant ambers, a carbon filter is provided inside.

You don’t need any special skills to connect this pump, you just need to remember to wash the drive from time to time.

Here are approximate prices for such units:

Which is better - submersible or surface?

With the same output pressure, a submersible sewage pump consumes less power than its external self-priming counterpart. The former simply does not have to waste energy on sucking wastewater through the outlet from the bottom of the container to the working chamber. All the power of the electric motor is spent on creating pressure in the pressure line.

A pump completely immersed in wastewater produces an order of magnitude less noise than one installed on the surface. Water absorbs most of the sounds produced by the electric motor and the rotating working elements of the pump.

Surface equipment is noisier than equipment immersed in a sewer tank, which is cooled by the liquid around it

In terms of ease of use, the palm can be given to the surface model, but only if it is compact and portable. Plus, the correctness of its operation can be monitored simply by the noise it makes. If the electric motor does not operate correctly, extraneous sounds appear, immediately indicating problems.

With all other parameters and additional equipment being equal, a surface pumping station will almost always cost less than a submersible sewage pump.Of course, a lot depends on the manufacturer and competition in a particular region.

However, equipment immersed in sewage is, by definition, more technologically advanced and more complex, which determines its higher price.

How to choose pumping equipment correctly?

When choosing a pump for pumping out sewerage, you need to pay attention to the many technical characteristics specified in its passport.

For example, performance parameters can help you estimate the time it takes to empty a wastewater tank. The higher this indicator, the more the unit will be able to pump liquids, but also the more energy it consumes for this. There are many other nuances.

The first factor is the maximum pressure and lift height

The pressure indicator determines the height to which the sewer pump can lift wastewater along the pressure line. But here it is important to understand that in addition to the vertical, there is also a horizontal section of the outlet pipe.

Simplified, to calculate this parameter, the horizontal distance is divided by ten and added to the vertical footage from the pump to the edge of the container.

The calculated figure for the required lift height should be less than the maximum pressure indicated in the sewer pump passport by 20–25% (+)

However, this calculation is very simplified; if everything is done according to the rules, then you need to take into account:

• composition and temperature of the liquid, as well as the size of impurities in it;
• the level of roughness of all pipes (material of their manufacture);
• pressure loss when passing shut-off valves;
• diameter of pipelines;
• Atmosphere pressure;
• speed of wastewater movement and much more.

All this must be taken into account in the design of the sewer system, which only a highly competent engineer can do correctly.If you don’t have the appropriate knowledge, then you can’t do without consultations.

Or you will have to use a pump for pumping out sewage with a large reserve of power and pressure, otherwise it will not work properly for a long time.

The second factor is operating temperature

All pumping equipment for domestic sewage is divided into two categories:

• for cold waste – with operating temperature up to 45⁰WITH.
• for hot waste – with operating temperature up to 90⁰WITH

If only cold water is drained into the sewer system, then it is better to take the first option, which is cheaper. In most cases, these pumps are installed in cottages. In fact, boiling water can only enter the sewer system of a private home during emergency discharges from the heating system.

The third factor is the presence of automation

It is problematic to control the operation of a sewer pump manually, constantly turning it on and off. It will be necessary to remain close to the equipment at all times.

It is much better if the pumping equipment kit includes:

1. Float – determining the level of wastewater in the storage tank in order to start and turn off the equipment.
2. Thermal relay – triggered when the temperature of the electric motor critically increases in order to turn it off before overheating.

To reduce the likelihood of clogging of a sewage pump with a built-in grinder, some manufacturers provide a self-cleaning cutting mechanism.

This allows you to increase the periods of operation of the unit without interruptions and stops for maintenance. Automatic cleaning ensures that the risk of overheating of the electric drive is reduced.

The degree of grinding of waste found in waste directly depends on the structure of the shredder impeller - for knives it is higher than for the cutting edge (+)

The fourth factor is power supply and housing material

Various models of sewage pumps can be powered from a single-phase or three-phase electrical network.

The first option is cheaper and preferable in Russian conditions, so in case of problems with voltage it can be connected through a stabilizer or simply connected to a portable generator.

For three-phase pumping equipment, you will have to purchase additional control panels to protect it from phase imbalance in the electrical network. And this means additional money and difficulties in connecting.

The most reliable pumps for pumping out sewerage waste are those with both the body and the working part made of metal.

Often the pump housing is made of cast iron or stainless steel. Plastic analogues are cheaper, but in aggressive environments they will last less without repair.

A compromise between cost and reliability can be considered equipment with a plastic body but metal working elements.

The choice of pump also depends on the expected loads. At arrangement of sewage system at the dacha For seasonal living, low-power surface or submersible units are suitable.

To organize the drainage of wastewater from a private house, it is better to use sewage pumping station.

Conclusions and useful video on the topic

How to choose the right drainage and fecal pump:

Review of submersible fecal pump with grinder:

Compact pumping equipment for inserting into a sewer pipeline in a house:

The choice of pumps for pumping wastewater from the sewerage system is huge. Without competent recommendations, it is difficult to navigate this issue.

Before going to the store, you need to decide on the performance, the height of the drain and the operating temperature of the equipment. If you take the equipment with a reserve in all respects, then you can greatly overpay, and if there are mistakes in the calculations, it will quickly fail.

We invite all site visitors interested in choosing and using a sewage pump to leave comments and ask questions. The contact form is located in the lower block.