Manholes - sewer shaft and manhole cover (concrete, plastic)

1. Sewer manholes

The inspection chamber, or manhole as it is more commonly known, is an indispensable part of the sewage system and is installed at the same time as the pipes and other services. There are many different types of sewer manholes on the market. Precast concrete and plastic manholes (polyester, polyethylene, polypropylene) are most commonly used. Our platform will provide you with the contact details of various contractors who will advise you on the most suitable choice and the appropriate diameter, height, and other characteristics for your specific case.

1.1. Standard sewer manholes

Standard manholes usually consist of a concrete pipe in which holes of a certain diameter, as specified by the planner, are drilled to connect the pipes. The only difference between a stormwater manhole and a sewer manhole is the type of cover as the latter must be impermeable to avoid the spread of unpleasant odours.

1.2. Drop manholes

A drop manhole is usually built at the special request of the local authorities. It differs from a regular manhole only in how the connecting pipes enter it. In regular manholes the pipes entering and leaving the manhole are at the same level, usually the bottom. In a drop manhole, however, one pipe enters the shaft at a higher level than it leaves.

2. How is a sewer manhole installed?

An inspection shaft can be installed in several different ways and there are several models. Sewer manholes also differ from manufacturer to manufacturer, so when installing them, it is vital that the accompanying instructions are strictly adhered to. Precast or prefabricated shafts are usually of better quality, because they are impermeable, faster to install, and cheaper.

2.1. Excavating a pit

A sewer manhole can only be installed properly if a pit of an appropriate size and depth is first dug out. Gravel or sand is poured into the excavated pit to form the subbase. Due to their light weight, plastic manholes can be installed manually, while concrete manholes require the use of machinery and also the bottom of the shaft needs setting in concrete. In order to be solid, stable and safe, the manhole must have a firm subbase. Special care needs to be taken to ensure that the fill material is well compacted, particularly where the bottom of the shaft will rest. If not, the manhole can easily get damaged or start to move.

2.2. Manhole connection pipes

All connection pipes to the manhole must be properly sealed to prevent leakage and deformation. The shaft height depends on the surrounding terrain and a cover is always placed on top.

2.3. Construction and structure

Where sewer pipes, stormwater pipes, water pipes and even electrical cables intersect, the correct installation sequence must be followed. First, the manhole shaft is installed and then the sewage pipes. However, these pipes and all the joints must have a minimum slope of at least 2%.

3. Concrete or plastic manholes?

Sewer manholes are made of only two types of material: concrete and plastic. Concrete manholes are used not only for sewage, but also for stormwater drainage. They are by far the cheapest option. Plastic manholes are more expensive, but they have the advantage that they are very easy to clean due to their smooth inner surface. They also have much better quality pipe sockets, meaning it is easier to ensure the joins are sealed than with concrete manholes. The quality of these connections is crucial for the durability of the entire shaft and, if installed properly, it should last for decades without any problems.

4. Manhole covers

A manhole cover is a key feature of the structure as it covers and secures the manhole and also masks it as it is usually situated in a visible part of the yard or garden. There are several options when it comes to covers. The cover can be made of metal, which is most often the case, although concrete or plastic ones are quite common, too. A manhole cover must be easily accessible and easy to remove and replace. At the same time, it should be sufficiently heavy and stable so it does not pose a potential danger when walked on. We recommend choosing a cover that will blend in visually with the surroundings or placing flowerpots on top of it to hide it.

5. Sewer manholes - price

How much does a manhole cost? The price of a sewer manhole with a protective cover and frame, including installation and connecting up of the pipes, ranges vary. The price depends mainly on whether it is a concrete or plastic manhole, which is the more expensive option, but also on the method of installation and the type of connections.