Septic pump gone berzerk

Old 09-04-02, 04:01 PM
Thread Starter
Join Date: Mar 2001
Location: USA
Posts: 57
Upvotes: 0
Received 0 Upvotes on 0 Posts
Septic pump gone berzerk

We have a two tank septic system that has a pump in the second tank to pump waste water to the septic field. Something has gone wrong, perhaps with the pump float switches, and the pump is clicking on and off every couple of seconds.

After waiting a few weeks to get a plumber to come out, I decided to open the second tank cover and see if I could spot anything obviously wrong. Here's what I see.

The system seems to have two or possibly three float valves. The current water level seems to be just a few inches deep, and looking at the residue inside of the tank, I believe the tank has normally had a level a couple feet deeper than it is now. There is one float valve that is floating lazily near (what seems to be) the pump pipes. A second float is hanging in the air a few feet above the current water level.

I ran water down a drain in the house with the pump switched off for a few minutes to see what would happen. Then I switched the pump back to automatic. The pump seemed to run continuously for a while; I went out to the tank. I saw what seemed to be water pouring out near the top of the outlet pipes, back down into the tank. When I went back into the cellar, the pump relays seemed to be back to the bad behavior of cycling on and off repeatedly.

I didn't see any obvious obstruction of the float valves. I was suprised to see the water coming out of what seems to be the outlet PVC pipe; this is an L shaped pipe that goes out to the field, then down near the bottom of the tank. The water was pouring out near where the pipes are joined at 90 degrees, but if there was a problem, the water seemed to come out of the wall of the pipe, rather than from where the pipes join.

All observations are rough. I didn't stick my head too far down into the tank.

Any ideas? Thanks!
Old 09-04-02, 04:58 PM
Trying2Help's Avatar
Join Date: May 2001
Location: USA
Posts: 771
Received 11 Upvotes on 8 Posts
I don't know jack about these things, but let me take a guess here and see how I do.
There are two floats, connected to an electrical contact. The lower float would control when the pump turns off, tank empty. The upper float would turn pump on, tank full.
If the upper float or contact for float, malfunctioned it would signal the pump to come on. However, the pump can not come on until the bottom float is also closed. Thus the lower float reaches a level to turn the pump on, the pump turns on. Pumping some water out of the tank, turning lower float off...pump goes off. Water level rises again, from water running back in and the pump comes on again.
If this is the case, I would start looking for a faulty upper float assembly or stuck relay on that leg.

Wish there was a way of drawing a picture here, as it makes sense to me, but I don't know if it will to you.

Well, Old Guy, how did I do?
Old 09-04-02, 05:55 PM
GregH's Avatar
Super Moderator
Join Date: Jan 2001
Location: Manitoba
Posts: 10,237
Received 66 Upvotes on 61 Posts
You likely have two mercury type float switches in your tank.
One will be to turn the pump on and off and the other could be for a high level alarm.
It is possible that the one that is "floating lazily" could be the pump switch and has fallen from it's mount.
These switches are normally taped or tie-wrapped to a pipe in a position that gives proper level control.
Check it out to see if there is an alarm or maybe one is an old defective switch that was never removed.
Old 09-05-02, 12:18 PM
Trying2Help's Avatar
Join Date: May 2001
Location: USA
Posts: 771
Received 11 Upvotes on 8 Posts
How many relays to you have in the cellar? If there are two, which I assume, is both of them clicking on and off or just one? I am still thinking either one of your relays is stuck, or the switch is. You will need to test and Please get back to us.

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: