Pumping sewer into a septic tank. Bad idea?

[LukeL]

Our house has 2 bathrooms that are too far from the septic tank for drainage. We have installed 2 grinder pumps, and haven’t had any issues. They both fill up to about 50 gallons and then pump (all at once) into the 1000 gallon septic tank. They’ve been in operation for about 7 years now.

 

[TractorGuy]

I don't see where it should be a problem. The solids should drop out in the tank and the liquid should overflow no matter how it gets there.

Are you sure a single system will pass for new construction?

When I had my house built back in 93 I had to have a separate system for the washing machine vs the rest of the house and bathrooms. We already had a 1000 gallon tank and 600ft drain field on our mobile home and they let us use that for the washer. The house required the same size system for the rest so I have two nearly identical systems but both are gravity fed.

It is curious to me why they didn't plumb the kitchen sink and dishwasher into the clothes washer system but they only put the clothes washer into the old tank. They are all along the same wall and it would have simplified the drain route to have those items included in one tank and the bathrooms on the other.

 

[ROUSTABOUT]

I’m working on a on a job now where a house is being built and they want to use an existing system. They planned on doing this from the start and the existing system was designed and permitted for the load so no problems there. But there’s not enough fall to gravity drain it. I’ve done sewer pumps before but they either pumped effluent into a leech field or they pumped raw sewer into a city sewer. I’ve never pumped raw sewer into a septic tank before. So the reason for concern is will a sudden surge of say 20-50 gallons into the tank at one time cause any problems into the septic tank?

A sewer pump works just fine. Have put them in and used for years. They are heavy duty and will give years of service. When the float switch turns it on it pumps the unit until empty. You can run a 2" line from pump to septic tank. I have one of the pumps out of one and I have pumped a few septic tanks out with it. They are grinder pumps and handle solids easily. Only problem is when electricity is off. Which, when you get more up town, you'll have up town problems. But if you live out of town, should have some type of other power source.

 

[4570Man]

I don't see where it should be a problem. The solids should drop out in the tank and the liquid should overflow no matter how it gets there.

Are you sure a single system will pass for new construction?

When I had my house built back in 93 I had to have a separate system for the washing machine vs the rest of the house and bathrooms. We already had a 1000 gallon tank and 600ft drain field on our mobile home and they let us use that for the washer. The house required the same size system for the rest so I have two nearly identical systems but both are gravity fed.

It is curious to me why they didn't plumb the kitchen sink and dishwasher into the clothes washer system but they only put the clothes washer into the old tank. They are all along the same wall and it would have simplified the drain route to have those items included in one tank and the bathrooms on the other.

They’ve never done that here. It’s probably the best thing you could do though.

 

[PILOON]

Mine gravity feeds into the 2 chamber settling tank, and then the effluent drains out into a pump tank, which pumps up to the septic field. I have had the pump in the chamber fail, and then fail again when I replaced it with a cheap pump. However, I now have a $400 killer pump and I don’t expect any more problems.

It would be nice to have the whole thing simply gravity fed, but I just don’t have the topography for it.

Also have a similar setup going on 25 years now.
Pump is also in a separate 'pump tank' and due to topography I pump up 20 ft to my field.
Upon advice I installed a check valve near the pump but with a small hole to allow a slow drainage of the 20ft of liquid back to the pumping station.
The purpose of the drain hole was to relieve the pump from start up stresses and also served me well from freezing as I could barely bury that pump line.

One tip I can offer is to very carefully seal all wire connections as the vapors in a pump station are very corrosive. (I learned the hard way)

 

[4570Man]

Also have a similar setup going on 25 years now.
Pump is also in a separate 'pump tank' and due to topography I pump up 20 ft to my field.
Upon advice I installed a check valve near the pump but with a small hole to allow a slow drainage of the 20ft of liquid back to the pumping station.
The purpose of the drain hole was to relieve the pump from start up stresses and also served me well from freezing as I could barely bury that pump line.

One tip I can offer is to very carefully seal all wire connections as the vapors in a pump station are very corrosive. (I learned the hard way)

I don’t think you’d want a hole in the check valve. A 2” line holds a lot of water and you’d be making the pump cycle a lot while not actually doing much. You’re really supposed to make all pump connections in a separate box and seal the conduit leading into that box. They make a putty that stays pliable to seal the conduit with.

 

[oosik]

I go by gravity to a two compartment septic tank with an outlet filter. Then by gravity to a 1250 gallon pump tank. A heavy duty sewage pump pumps effluent to a pressurized drain field. Been in operation for 14 years. Works just fine.

Every six months I pull and clean the outlet filter on the septic tank.

 

[310-510]

5 years now without any trouble on my Liberty 41 gallon sewage pump. Easy install.

 

[Popisin]

Assuming the pump is a grinder pump there's a good argument that this is a superior solution to gravity.

It's pouring a soup into the septic tank which is more amenable to decomposition and diluted which makes it that much easier to navigate the leach bed.

As unlucky RV'ers will tell you, it's a chore when solids pile up in a tank. No difference a septic tank and a Winnegbago tank in that regard.

 

[Dennis59]

I’m working on a on a job now where a house is being built and they want to use an existing system. They planned on doing this from the start and the existing system was designed and permitted for the load so no problems there. But there’s not enough fall to gravity drain it. I’ve done sewer pumps before but they either pumped effluent into a leech field or they pumped raw sewer into a city sewer. I’ve never pumped raw sewer into a septic tank before. So the reason for concern is will a sudden surge of say 20-50 gallons into the tank at one time cause any problems into the septic tank?

I have a set up where the drain field at a higher elevation then my septic tank. I used a lift pump to the drain field. It uses a 2 compartment tank where the solids stay in the first section and the liquid flows to the second and gets pumped up to the drain field. Depending on the requirements in your area I would think it would no cost much to drop in a new tank and gravity to it and pump to the drain field. I the 20 plus years I only had to replace the pump once and that was @15 year old