How Big Do I Need My Septic Tank To Be?

In the UK, we use a simple rule of thumb for sizing a septic tank, that is the volume of water per day + 2000L. We have a full guide on sizing a septic tank which can provide you with the detailed calculations, however for ease, here is a table to help:

Number of bedrooms: Minimum tank size
1-3 bedrooms 2750
4 bedrooms 2900
5 Bedrooms 3050
6 Bedrooms 3200
2 x 2 bedrooms 3200
2 x 3 bedrooms 3500
2 x 4 bedrooms 3800

There is no harm in going slightly larger in size, it will allow slightly better settlement of solids which could lead to less suspended solids getting into your drainage field.