After reading up on battery backup sump pump systems I'm still wondering what's good. The wife says "Who needs 30 minutes to 1 hour of pumping if you lose your power during a storm?"
You'll need a generator to keep running for hours. But if you want to have a generator kick on when you are not home that would be a very pricey solution, I would think. Before spending a dime on finishing my basement I want it to be as water proof as possible (and reasonable). Wassup?

 

I don't think there is a single answer for everyone. I have seen Sump pits full of spider webs because they never got any water in them. I have seen other pits that are pumping out water in the middle of a dry spell.

You need to consider how many times the pit fills and is emptied during the hardest and longest rain that you want to plan for. If you get a monsoon twice a year you better plan for that. You also need to consider how often the power goes out and how long it stays out.

Bottom line-
What is the cost if you over size the solution and what is the cost if you undersize the solution.

One other tip-
Eliminate as much water near the perimeter of the house as possible. Look at the landscaping and terrain.

 

What about building a retaining wall around the sump hole? I constantly have water coming into my sump hole (I think I am below the water table). The electric pump kicks on about once every hour and a half. I have a battery backup, but you never know when both pumps will fail to kick on. It only takes having water in the basement one time to ruin everything.

 

Sbell,
Your idea has some merit, but you still have the problem of the pit (which you made larger) filling up- at some point it may overflow or leak.

You are talking about a lot of water. Water weighs about 64 lbs per cubic foot (or 8 lbs a gallon). Will the wall you build be water tight and strong enough to hold the water? To accomplish what you want to do, you need to create a water tight seal from the top of the existing pit to the botom of your enlarged pit. I suspect that a wall would leak until the day you die.

I would again suggest that sbell consider the volume of water and the time it takes to fill the pit. If he has a 30 gal. pit and it takes 5 minutes to fill during a typical rain, he is going to have trouble even if he builds a wall and creates a 200 gal. pit. When my power goes out, it stays out for either a second or two, or for hours.

Another point-
The existing pit is below floor level. If you extend the pit above the floor level, water will only rise as far in the pit as it is outside the foundation. The point of the pit is to take water away from the outside of the foundation and from under the floor. A pit extending above the floor will not accomplish this. In fact, if the water were to constantly fill the pit, there is a chance that the hydraulic force of the water against the foundation would cause the wall to bow in. I am not an expert, but I think the net effect of building this wall could be the same as blocking the inlet to the pit and not letting any water in.

In, my opinion you have these choices:
1) Buy a battery backup pump;
2) Buy a generator that kicks on when the power goes out; or
3) Eliminate the pit and re-configure the drain tile to drain out a pipe that extends into the yard where the terrain allows for enogh slope in the pipe to create a natural drain. This is always the best solution. Unfortunately, it is not always possible.

Note: I am the only house in the neighborhood that did option 3, and I am the only one that has never had any water in the basement. I also don't worry about my finished basement when the power goes out. I do get a workout in my neighbors basements...