Sewage Ejector Pump — Inside or Outside?
I’ve searched through the archives on this group, and there seems to be differing opinions regarding whether to install a sewage ejector pump and basin inside or outside of the house. Most say they install it inside, but a few (and one was rather emphatic) said to bury it outside if you have the space.
Ten years ago, my septic system failed, and I hired a plumber to install a connection to the municipal forced main sewer.
He did a terrific job, but during the installation we had a difference of opinion. He wanted to install the pump and basin in the unfinished basement, but I wanted him to install it outside. My theory was that when it failed, I didn’t want the mess in my house. Well, last week it failed, and now I’m reconsidering that decision. There was no mess (the pump switch was stuck “on”, not “off”!) and what should have been a two-hour repair ended up taking two days because of all the excavation. Fortunately the ground wasn’t frozen when it decided to fail. I’m thinking about moving the pump inside now, because I want access to the pump for inspection and repair, and I’m getting too old to be digging that thing up.
So what are the pros and cons to locating the basin and pump inside versus outside? Is it worth the effort to move it inside, and are there things which I am not considering which will make me regret that decision?
Replies
Where I live the old sewer system was replaced with a forced main system.
All of the house in the city, about 350 homes.
They are all OUTSIDE.
But there is no problem with access.
They are large tanks, about 30-36" dia burried in the ground with the top just above the ground.
The pump hangs in their on a quick disconnect pipe connection, similar to the pitless well pump adapter. And a plug for the electrical.
If the bolts holding on the lid are frozen or don't break lose and spin out when removing them they can remove and replace a pump in 30 minutes.
And I am glad that it is outside and not inside.
Last year, twice I had failures that caused the force main to feed back into my tank and overflow.
BTW, there where lots of tomato seeds in that sewage. I had lots of volunteers around the tank.
If you just need a lift for basement drains, it makes more sense to imbed it in the basement floor. If you're replacing a septic tank system, it may make the most sense to install a sump in place of (or next to the abandoned) septic tank.
But, as you found, a pump is a device that must be serviceable and shouldn't require excavation to access. If the outside installation can't be arranged with manhole access then inside installation should be strongly considered.
An inside pump can be arranged with safety alarms and even an auto water cutoff, if you wish, to virtually eliminate the chance of a backup. [And a proper installation should include a check valve that would eliminate the hazard of a sewer main backup.]
Edited 9/10/2006 2:27 pm by DanH
Here are some examples of outside systems.
http://pasture.ecn.purdue.edu/~epados/septics/sewer.htm
http://secure.data-comm.com/RBIS/Detail.bok?no=222077
http://www.eone.com/sewer_systems/products/grinderpumps/gatorgrinder_index.htm
http://www.aermotorwindmills.com/zoellergrinderpumps.htm
http://www.eone.com/sewer_systems/products/grinderpumps/1000_index.htm
http://www.eone.com/sewer_systems/products/grinderpumps/2014_index.htm
http://www.premierplastics.com/pumpout.htm
I've seen it both waysl, but more outside.
Maybe the local frost line has a lot to do with it. Here the exterior tanks are not burried. The access is at grade...
Also has to do with slopes, existence of basement, etc. The pit has to be lower than any of the drains in the house. For a basement a simple deep sump will work, but outside you may need to go down 15 feet or more, if the slope isn't working in your favor.
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
As DanH and Bill point out, whether the pump is inside or outside, it should be installed with a riser on the pump chamber to allow easy access. Based on what I've seen with sewage pump and septic pump failures, I'd rather install the pump outside if it serves the entire house, even though the alarm should warn you of a pump failure before the pump chamber overflows.
Right - and set the alarm float switch high. They are no fun to adjust after the fact. Guess how I know :-)
I installed a Liberty sewer ejector in my shop and decided to put it indoors. The outlet pipe comes out the top and I could not see how to freeze-protect the thing without building some sort of elaborate underground vault for it. So, it's indoors in semi-conditioned space under the stairs. I left a 2' x 3' hole in the slab where the unit is installed, and the lid is level with the slab, so in theory I could dig the entire thing out and install a new one without much drama.
Thanks for your response, David.
I am leaning in the direction of moving it indoors, too. Accessability is just too important to have the thing buried. Here in NJ, I belive the frost line is only about 30 inches, but I am concerned about freezing as well if I go to the trouble of building a vault type of thing (not to mention the eyesore that would create in the front yard.)
One specific question for you: Since you installed yours indoors, have you had any trouble with odors? These little plastic basins are supposed to be airtight, but from your experience, do you find that to be the case?
Thanks again, David.
My unit is almost exactly what is shown in this picture, minus the big hole in the side.
http://www.plumbingstore.com/sewagepackages.html
It's vented thru the roof with 2", the other hole in the lid being the 2" outlet. My assumption is that the 2" outlet riser coming out of the lid is always full and could potentially freeze. The space under the stairs in my shop is accessed thru a small door from the exterior, and while not directly heated it is within the insulated envelope.
Old timers here tell of hard freezes and skating on ponds in winter. Global warming has changed that, but we still get a couple days or a week in the teens and twenties each winter.
In NJ I think anything in a vault would be safe, especially if you put a few inches of foam on top. Remember that the incoming sewage keeps things warm, and most of the vault would be below that 30-inch mark.
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
May be a code question, does your local code give you the option? If you can put it anywhere that you want I would go with the inside installation. If you are going into a force main I would go with a dual pump set-up even if the local code dosen't require it. Get all the safety devices that come with the system and you will have very little chance of ending up with a flood. Where I live outside installations usually have a structure built over them. FYI I've installed them in five story buildings and they are all inside. Lots of luck. ______________________________________________________________________
Thank you all for your thoughtful responses to my query.
I've decided to move the pump inside the building into the unfinished basement. In addition to your responses, I also met with a couple people at the MUA today. There doesn't appear to be any code issues; these little sump basins are approved for both indoor and outdoor use.
The MUA people told me that my biggest concern would probably be backup, in the event of a failure of my check valve. It turns out that my location is ideal to mitigate this concern, as the forced main turns into a gravity main at the next house down the street. In addition to this, my house sits pretty high, so I can keep the discharge pipe for my basin above street level. Because of this particular situation, it would have to be a pretty unlikely combination of circumstances to cause a backup into my basement. I was also concerned about infiltration of sewer gas, but in thinking about it, it shouldn't be a concern. First, the check valve, which is mounted in a vertical positon, should remain closed when the pump is not operating; and second, there is enough water remaining in the basin after a pumping cycle to cover the bottom of the discharge pipe, thus creating a trap of sorts.
So I appreciate all of your thoughtful comments which really helped me think through this issue. I will rest easier because of your help.
Now an amusing story:
What started this whole thing is that I started getting an alarm on my tank. After awhile, it would stop buzzing, so I figured that the pump was going bad or clogging. My girlfriend, who is not very mechanically inclined, but very intuitive, said that she thought it was roots. Impossible, I said; the entire sewer line is PVC cemented together; there's no way roots can get in there. Some time later, we noticed that every couple of hours the pump would run for about ten minutes, and then shut off. A couple hours later, and the cycle would repeat, regardless of if we were using any water at the time. I figured it was a bad check valve, and that my pump was fighting the municipal pumps when they cycled on. So I dug up the thing, and went out and bought the best darned check valve I could find. I put it in the discharge line, and when I was sitting back admiring my work, the pump started again. It ran for ten minutes, and then stopped. Darn. Wasn't the check valve, I guess. So I dug some more, and removed the pump. It turns out that one root, smaller in diameter than a pencil, had worked it's way into the sump past the flange, which is clamped to the inlet pipe. It had grown down to the bottom of the sump, where all the water and nutrients are, and started growing in circles around the bottom. With each new trip around the bottom of the sump, it lifted the float switch a bit further. Well, this root ball ended up filling a five gallon bucket when I pulled it out of there, and it had grown so much that it held the float switch up and would not let it switch off. The pump would pump for about ten minutes, and with nothing to pump, it would overheat, then the thermal switch would trip. A couple hours later, it would cool enough to reset the thermal switch, and the cycle would start again.
Roots...go figure.
Thanks again, everyone, for all your help.
You've made your decision, and if I had it to do, I would also install inside.
We moved into our 60's era house 8 years ago, and one month later the heretofore unknown sewage ejection pump that was buried in the yard failed. It served the entire house. We found out it existed when the rooter guys got their equipment stuck and then pulled out wires (they'd wrapped around the pump) when they finally yanked it free. The thing was buried under the grass in a collapsing wooden vault. We dug it out and used steel culvert to make a chamber, added insulation over the top and made a cover for our brand new pump. So now we can access it (and it's existence will never be forgotten), but I worry when it gets bitter cold. So far so good, but we are due for a new cover and fresh insulation. If our basement wasn't finished, we could have it in the house and I would worry less (or at least find something else to worry about).
We spent several thousands of dollars this year replumbing the house so we could avoid using the pump for the main floor.