Pumping sewer into a septic tank. Bad idea?

[4570Man]

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?

 

[Jchonline]

Can you do it in smaller amounts over a few days? If so that would mimic actual use.

 

[4570Man]

Can you do it in smaller amounts over a few days? If so that would mimic actual use.

I could make the dosing cycle whatever I want but the smaller it is the more frequently the pump will cycle.

 

[JJT]

20 - 50 gallons at a time into a 1000 gallon or bigger tank is not going to cause an issue. Lots of houses have basement bathrooms and laundry rooms with grinder pumps pumping up to a septic tank.

 

[4570Man]

20 - 50 gallons at a time into a 1000 gallon or bigger tank is not going to cause an issue. Lots of houses have basement bathrooms and laundry rooms with grinder pumps pumping up to a septic tank.

I haven’t looked at the original build specs but it was permitted for 4 bedrooms. So it’ll be minimum 1000 gallons.

 

[Jchonline]

My dosed septic for 3 bedrooms is 75gal 4 times a day. SOrry I thought you meant a 1 time drain of 20-50 gal.

 

[RjCorazza]

My tub holds just under 80 gallons to the overflow. After 23 years on a septic system we have never had a problem. I have also periodically dumped 40 gallons of sewage from an RV without issue.

 

[4570Man]

My dosed septic for 3 bedrooms is 75gal 4 times a day. SOrry I thought you meant a 1 time drain of 20-50 gal.

But that’s pumping effluent into a leech field isn’t it?

 

[Rustyiron]

Good question
Are you gravity to a pump vault then forced to the existing tank? A 300 gallon (?) pump vault would keep the pump outside and be able to act as a "buffer" during heavy use times.
I've never worked on something like this, but as I remember, there's a good bit of floats and alarms involved so that a (****ty) problem in the house doesn't occur. Does your town or county have requirements (advice) for this set up?

 

[4570Man]

Good question
Are you gravity to a pump vault then forced to the existing tank? A 300 gallon (?) pump vault would keep the pump outside and be able to act as a "buffer" during heavy use times.
I've never worked on something like this, but as I remember, there's a good bit of floats and alarms involved so that a (****ty) problem in the house doesn't occur. Does your town or county have requirements (advice) for this set up?

Yes that’s how it’ll work. The local septic inspector is incredibly unhelpful.

 

[Rustyiron]

Septic systems seem to be lost between the guy with the heavy equipment (installer) and the plumber depending on the system. Got any plumbers you trust?

 

[Jchonline]

But that’s pumping effluent into a leech field isn’t it?

Yes we have 3 tanks with our setups in CO. Solids, effluent, then dosing tank. Tanks are gravity fed, but the dosing tank pumps 75gal 4 times a day into a pressurized leech system.

 

[4570Man]

Yes we have 3 tanks with our setups in CO. Solids, effluent, then dosing tank. Tanks are gravity fed, but the dosing tank pumps 75gal 4 times a day into a pressurized leech system.

Why do they have 3 tanks? Locally the effluent and the pump tank is the same one.

 

[Jchonline]

Why do they have 3 tanks? Locally the effluent and the pump tank is the same one.

I misspoke, my apologies. The septic is 2 chambers itself..effluent isnt completely separate.

 

[grsthegreat]

I hook up dosing pump systems all the time here only thing allowed for new systems near lake or high water table areas.
but i also wire in lots of sewage pumps that send waste to septic tanks. Companies here have done that for many trouble free years.

worst thing that happens is pump fails……a crappy job to fix. personally, i never work on existing systems. All my work is new systems only. Not enough money in the world to dig into a used septic pump.

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[4570Man]

I hook up dosing pump systems all the time here only thing allowed for new systems near lake or high water table areas.
but i also wire in lots of sewage pumps that send waste to septic tanks. Companies here have done that for many trouble free years.

worst thing that happens is pump fails……a crappy job to fix. personally, i never work on existing systems. All my work is new systems only. Not enough money in the world to dig into a used septic pump.

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I know pumps aren’t optimal. The only way to avoid that would be to install a completely new system. Which is probably what I would do but you know how that works. You can usually do a 3 bedroom gravity system for about $4500 here. We’ll have probably spent $3000 maybe a little more by the time the pump is done.

 

[Rustyiron]

Looking at all this might persuade your customer to just go for a new gravity system.
In all my years there's never been a time when you couldn't couldn't count on it.

 

[Rustyiron]

Nice, neat cabinet there grsthegreat.

 

[cqaigy2]

My cousin has a system where the house is on a steep hillside, sewage is pumped up from her house to a flat spot, where her septic system is. It was put in just a bit over 20 years ago. Pumps into a two chamber tank, from there gravity into leach field. She's had two problems, all caused by uphill neighbor so she said, one was broke pipe, the other was pump failure, i didn't hear how the neighbor was involved in that one.

 

[check]

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.