Sump pump

[DavidS]

Our new house has a sump pump in the basement. As you may recall, the house is new construction by a builder who went bankrupt. We bought it as a short sale for a great price, but do not have the benefit of going back to the builder with every question. So, I turn to you knowledgable folks. I've never lived in a house with a sump pump, so I don't know what to expect.

Anyway, when the pump turns on, it has a momentary, soft "whine" followed by a loud "THUMP." We were not yet in the house when Atlanta had the bad rain and flooding a few weeks ago. It started raining last night and has been pretty steady. This morning, we noticed the pump going off every 3-5 minutes. The basement is not damp, flooded, leaking. It sounds like water is going into the pit from the pipes, but I'm not sure where that water is coming from. Is it common to route water from the outside or under the foundation to this?

My wife is likely going to call a plumber, just to have him tell us that it is working fine, so I thought I'd pose the question here first.

[AllGold]

That thump is the sound of the check valve closing. That valve keeps the water that was pumped out from running back down the pipe and back into the sump pit.

Typically, houses are built with drainage tiles around the foundation which in turn drain into the sump pit. The sump pump obviously pumps the water out of the sump pit. This whole process keeps water away from the foundation and keeps your basement dry.

[davester]

If the pump is situated in a spot where disaster could ensue if it failed, you might want to ensure that your pump has a battery backup. Power failures always seem to happen during the big storms, right when you need that pump. In fact, some people go so far as to install a backup sump pump. If you go that route, then you simply install the backup (which should be the one with the battery backup) so as to turn on at a higher level than the regular pump. That way the backup stays pretty much unused until you really need it.

[MacArtist]

5. What is negative hydrostatic pressure... ?

In most areas of the country ground water starts to produce a column of water pressure that is exerted on basement walls normally starting from two to four feet below surrounding ground level. This water column or "natural hydraulic pressure" tries to equalize it's pressure by flowing to cracks or porous imperfections in your basement walls, footings, and floors.

[davester]

I don't know why you're asking, but negative hydrostatic pressure (i.e. pressure lower than atmospheric pressure caused by capillary action) occurs in the zone called the capillary fringe, which is the "tension-saturated" zone just above the water table. I'm not sure what this has to do with this thread though.

[Plumbking]

AllGold wrote:
That thump is the sound of the check valve closing.

:agree:

[rgG]

Plumbking wrote:
[quote=AllGold]
That thump is the sound of the check valve closing.

:agree:
I have a sewage ejection pump for a basement bathroom and the check valve makes that same sound after the pump stops. It can be quite loud, if you are standing right by the pipe.

[davester]

rgG wrote: sewage ejection

I just don't like the sound of that.

[rgG]

davester wrote:
[quote=rgG]sewage ejection

I just don't like the sound of that.
Yeah, to make it sound even worse, it is a macerating system.

[GGD]

davester wrote:
[quote=rgG]sewage ejection

I just don't like the sound of that.
I have one of those too, and hearing that sound is actually reassuring, what you don't want to hear is total silence over several flushes, that means the pump isn't coming on, and sh*t doesn't flow uphill on it's own.