Septic system expansion

[Ken Tannenbaum1]

Our 1980 house has two bathrooms and a septic that works very well. We're considering adding an addition to the house with a 3rd bathroom and don't know if the leach field was built for that load. How can I find out? There are no plans I know of that were originally filed. Thanks.

 

[Reach4]

I don't know, but if there are not going to be more people, and if the new toilet is low flow, the new bathroom may reduce the load on the tank.

If that addition is because of more people, I would ask your very experienced septic tank person. He probably knows what was commonly used in your area in 1980.

I am not a pro.

 

[Sponsor]

 

[hj]

Quite often the county health/building department has drawings of septic tank installations, so check with them first.

 

[Gary Swart]

If the old toilets are original to 1980, they certainly are at least 3 gpf and possibly as much as 3.5 gpf. I can promise you it would cost less to replace the old dogs with new 1 gpf models and install the same in the new addition than to rebuild the septic system.

 

[Smooky]

Septic systems for a house are usually sized for the number of bedrooms.
With pre-1980 fixtures the design flow would be 150 gallons per day per bedroom. With modern fixtures the minimum design flow drops to 110 gallons per day per bedroom.