I have been awakened several times in the early morning hours recently by activity in the pumps. The grinder and/or the ejection pump (two separate power cords supply power to each device) operate at times when I wouldn't expect them to run. The basement bath & toilet don't get as much use as the other bathrooms. If I fill the bathtub with water and then let it drain, the pumps will operate, ejecting the gray water into the normal sewer lines and the pumps quit running. Within hours, the pumps come on again and it seems like the grinder runs for no reason--nothing has been flushed and nothing has been run through the sink or bathtub. The catchbasin should just be empty but either the pump runs or the grinder runs.

When you say "grinder" do you mean garbage disposer ?

Is there a possibility that you have leaking toilets, dripping tub faucets or primed floor drains ? Also, any way ground water could be entering the sewer ejector pit slowly filling up the pit and activating the pump ?

I think he is talking about a macerating toilet. He might be getting some back flow which is tripping the float switch.

Here is what happens: I notice loud noises coming from the mechanical room in the basement. The room is adjacent to the basement bathroom. There are two noises. First, in the ejection pit a mechanical, pump-like noise that runs and runs. The second noise occurs when the pump actually kicks on and begins ejecting waste water from the pit. This causes the pipes to rattle and shake violently and the water then ejects to the house's sewage drains.

I spoke to the builder's service department that said I was dealing with a sewage ejection pit pump and grinder. There are two electrical devices involved. One is plugged into the second which is plugged into the wall in the basement.

The service dept. representative told me he suspected a stuck float because the plumbing doesn't get much usage. He suggested that I fill the bath a number of times an allow the system to cycle through draining/pumping more than normal. He thought the float might be stuck in the on position because of the constant running of the pump.

When I run a tub full of water then open the tub drain, I can hear the water draining into the ejection pit. After a few moments, the pump turns on and ejects the water. This happens several times as the tub of water is drained. Finally, all water is drained and the pump stops and the grinder stops as well. Problem solved until the next time. This issue has occurred for about the last week and I have run 15-20 bathtubs full of water through the system and it still seems to be occurring.

Do you think there is a float that is stuck? Does it sound like something might be lodged in the "grinder" or macerator? I can't identify the pump manufacturer or model number without removing the pit cover, which is bolted on and sealed. If I remove the pit, will I need to re-seal it with caulking or adhsive or are these systems just made with a rubber gasket as the seal?