Poor ventilation: check that the system is ventilated correctly through the stench pipe on the property/remote vent.
Tank requires emptying: if the primary tank is not emptied as recommended, this can cause odours.
Drainage field failed
The most common problem with a drainage field is that the drainage is backing up. This can be identified by checking the levels in the septic tank. The cause is likely to be a failed drainage field, which could be fully saturated due to poor soil conditions or a high winter water table, or a blocked drainage field due to solids carried over from the septic tank/sewage treatment system. If you do not maintain (arrange emptying of) your system, solids can pass through the tank and therefore block the downstream drainage field.
Generally, to rectify the situation, an engineer would need to replace the drainage field – jet washing may occasionally be an effective solution, but this is on a case-by-case basis and advice should always be sought by a qualified engineer.
System is overloaded: if too many people are using the septic tank for the size, it can become overloaded.
Tank requires emptying: if the tank is not emptied as recommended, this can reduce performance.
Chemicals and other biological inhibitors: high concentrations of detergents and cleaners will cause poor performance. The O&M manual for each system gives an overview of limitations, appropriate concentrations etc.
If you have concerns about your septic tank, give us a call on 01388 537030.