septic tank puzzle

[calvert]

We have a brick built septic tank about 20 metres from the house with the usual broken clay pipe that I supose was the vent. There is a stench pipe on the house. The house is 110 years old so I guess the tank is the same age. Can i fit a short length of pipe with an air admittance valve to the vent as its in the middle of the garden?

 

[Agile]

I think that they were expected to be open to the atmosphere! They probably let air OUT when water is flowing into the chamber.

Others from the country will advise though.

Tony

 

[Diggerjohn]

The vent pipe on the old tanks was to let the septic tank gases out, not to allow air in, so an air admittance valve would be defeating the object.

Septic tanks produce methane and hydrogen sulphide gases which must be relaesed to the atmosphere. They do smell, but in the old days, no-one cared too much.

Modern septic tanks have vents that do let air in, rather than out, but in all cases, the soil vent pipe, or stench pipe, must be within 10 metres of the septic tank on the drain run. If it is, then the SVP acts as a chimney and draws the air into the tank through the tank vent, through the tank and up thrugh the SVP, releasing the gases where it doesn't matter.

If your existing SVP is too far away to draw, you could always install another one within 10 metres, if you have a handy building to support it.

 

[calvert]

thanks for the replies, computers been broken! I will try and get another pipe located nearer the tank