Cesspools and Silage tanks

Cesspools and silage tanks are designed to collect and hold temporary wastewater and sewage. As single-chambered tanks, they don't treat the water in the way that septic tanks do and they don't release into watercourses. Therefore they need to be emptied regularly.

Depending on the size of the tank and the number of people in the property using it, cesspools may need emptying anywhere from annually to weekly. This can be costly to do and it's one of the reasons that cesspools are becoming less popular in the UK.

However, a cesspool may be necessary where it isn't possible to install a more economical septic tank or treatment plant option. Examples include campsites, farms, and industrial sites.

If you do need to install a cesspool, the bigger you can go the better. Building Regulations state a requirement of at least an 18,000 litre capacity for 2 users, giving up to 45 days holding, with an extra 6,800 litres added per additional user.

We'd always recommend overestimating the capacity needed when opting for a cesspool.

Cesspools and Silage tanks look mostly the same from the outside, and both are single-chamber tanks designed just to collect and hold wastewater and sewage.

However, cesspools are designed for household and business waste, whereas silage tanks are designed for agricultural waste.

Silage tanks have an additional internal liner that is in place to protect the tank from the effects of agricultural waste. This is because silage waste has a greater polluting potential. Every 500 tonnes of unwilted silage is equivalent to the untreated sewage of around 200,000 people.

Silage tanks must have a protective internal liner to safely hold agricultural waste.