I have a bathroom in the basement that is below-grade, and has a pump to send the sewage up to the main line and out of the house. It's working, I have no problem flushing the toilet or draining the tub there.

That bathroom is rarely used, and during the first few years in the house we almost never heard that pump activate. There is a 12 gallon cistern that the bathroom drains to, so it took multiple toilet flushes to make the pump go. Lately, though, I hear the pump turn on and water flowing through the pipe even when no one has used that bathroom in several days. Sometimes I hear it in the middle of the night, when I'm certain no water is turned on anywhere in the house.

So the mystery is - Where is it getting water to pump? Is other sewage from elsewhere in the house somehow draining towards that bathroom? Or could there be groundwater somehow getting into the cistern? I have no experience with this type of system, so I have no idea.

I thought it might be good to get some input here before I call a plumber.

Probably from a leaky toilet valve. Turn off the water to the toilet, flush it and see if it stops. If it does, rebuild the valves in the toilet.

Probably from a leaky toilet valve. Turn off the water to the toilet, flush it and see if it stops. If it does, rebuild the valves in the toilet.

Great answer! May not be the problem, but the first thing I would do!

Probably from a leaky toilet valve. Turn off the water to the toilet, flush it and see if it stops. If it does, rebuild the valves in the toilet.
Could be just the flapper valve in the tank at the bottom. Sometimse they distort causing a slow leak- Couple of bucks to replace. If water is running into the fill tube then replace the fill valve assy, about $20 for a kit. I would definately suspect the flapper though.

If it is not the toilet, then it could be a leaky sink, or tub valve. Maybe the foundations weeper system drains into it? Some have HVAC condensate drains in them too.

Is there a check valve?
Or maybe the grinder's internal works could be aged.

Is there a check valve?
Or maybe the grinder's internal works could be aged.

:yeahthat: If you don't have a problem with the toilet running you may want to look at the check valve as it may not be sealing properly and allowing waste water to leak back into the pit from the main line.

Thanks, those are all good ideas. Will definitely check the toilet. Not really sure how to figure out if the check valve is working properly, but I'll look into it. Now that I think of it, there is a distinct *clunk* noise at the end of the pump cycle (that's the only reason that I know the pump has run) so maybe that is the source of both the noise and the extra cycling?

It's the random timing that has me the most confused. I happened to be awake around 4:00 this morning (restless 3 year old woke me up) and heard it run. Why at that exact moment, when no one has used any bathroom in the house for hours? That has me thinking maybe it is a slow leak from the toilet. :confused:

Thanks, those are all good ideas. Will definitely check the toilet. Not really sure how to figure out if the check valve is working properly, but I'll look into it. Now that I think of it, there is a distinct *clunk* noise at the end of the pump cycle (that's the only reason that I know the pump has run) so maybe that is the source of both the noise and the extra cycling?

It's the random timing that has me the most confused. I happened to be awake around 4:00 this morning (restless 3 year old woke me up) and heard it run. Why at that exact moment, when no one has used any bathroom in the house for hours? That has me thinking maybe it is a slow leak from the toilet. :confused:

The clunk is normal. It's the grinder pump slamming after it pumps out.

There aren't too many sources of water that would make it run, but the toilet is the most likely culprit.

Why at that exact moment, when no one has used any bathroom in the house for hours?

Ghost with a full bladder? :lmao:

Actually I agree that it sounds like a slow leak in the toilet.