Choosing the correct size Cesspit
Installing the right size cesspit will ensure you adhere to building regulations. Get it right and you wont have to empty the tank too often.
This step by step guide is all you need to calculate which tank will be right for your property.
This guide is intended for cesspit sizing for domestic properties. I've written a separate guide for cesspits for commercial buildings. Sizing of a cesspit for a commercial building is very different so i would encourage you to read it.
A cesspool is the same as a cesspit. A cesspit is a holding tank that stores wastewater. It has no outlet and consequently, once full, the tank will need to be emptied. It is common to confuse the term cesspit with a septic tank.
The difference between a cesspit and a septic tank is simple: A septic tank retains solids and allows liquid to be released into the ground, whereas a cesspit retains all the water and solids.
When there is no way to treat and release water into the environment a cesspit is often the only choice. This can be for the following reasons:
It is building control that govern how large a cesspit needs to be. You can obtain Part H of building regulations for free. I would suggest doing this if you are planning to install a cesspit. Part H of building regulations state that:
1.61 Cesspools should have a capacity below the level of the inlet of at least 18000 litres (18m3) for 2 users. This size should increase by 6800 litres (6.8m3) for each additional user.
Part H building regulations
Remember to include and outhouses and consider if you might extend or do a loft conversion.
You can calculate how many people there will be in the property by using the number of bedrooms as a reference. There is no guidance from building control as to how to do this, subsequently, the below guide is a good rule of thumb:
1 bedroom = 2 people
2 bedrooms = 3 people
3 bedrooms = 4 people
4 bedrooms = 5 people
5 bedrooms = 6 people
2 people = 18000 litres
3 people = 24800 litres
4 people = 31600 litres
5 people = 38400 litres
6 people = 45200 litres
Step 4 = Round up to the nearest available tank size:
| Number of bedrooms | Number of people | Minumum tank size | Tank size rounded up |
|---|---|---|---|
| 1 | 2 | 18000 | 18000 |
| 2 | 3 | 24800 | 25000 |
| 3 | 4 | 31600 | 36000 |
| 4 | 5 | 38400 | 40000 |
| 5 | 6 | 45200 | 54000* |
No, since a cesspit is a sealed tank there is no waste released into the environment so you do not need a permit
A cesspit holds all of the waste from your household or business. Subsequently a cesspit does not discharge any waste into the environment and does not need to follow general binding rules or require a permit. A septic tank, on the other hand does discharge waste into the environment. A septic tank is smaller and is designed to hold any solid mater, allowing the liquid to drain out of the tank and through the ground via a drainage field.
There is no difference, the 2 terms are used interchangeably
Maybe, it is site specific. If a cesspit has been installed it is likely to be because discharging to the environment is not possible. Some other alternatives are to drill a borehole and use a packaged treatment plant (you will require a license from the EA to do this).
yes, it is recommended to have a alarm to warn you when the tank needs to be emptied. These are commonly known as a "high level alarm". It can be audible and also have a flashing beacon.
When it is full. This will be determined by how large the tank is and how much water is being disposed into the tank.
The cost of emptying varies slightly throughout the UK. However it will be roughly £100 per 1000 gallons. 1000 gallons is approximately 4500 litres. Therefore a 45000 litre tank would cost £1000 to empty. You should check the size of the tank, and also estimate how much water you will be using (based on 150 litres per person).
The prices of tanks vary depending on their size. For households, the size needed will range from 18000 litres upwards, the cost of an 18000 litre tank can range from £3000-£5000
Smaller Cesspits are sometimes made from plastic. However, due to their size, larger tanks (10000 litres and up) are normally constructed using GRP (glass reinforced plastic).
Yes, Building Regulations Part H (2015) states that a cesspit must be vented. This is to prevent the acumination of gasses within the chamber.
You should put a low level vent off of the main chamber, and a traditional soil vent pipe coming out of the roof. Air admittance valves should not be used for Cesspits, Septic tanks or Sewage treatment plants.
I've provided a lot know free advice in the website. Which i really hope has helped you!
I'm doing some research and would like to know....