There is no limit to how much water you might pump.
Who knows how deep your basement will be flooded if the pump fails.
Or how many pump failures you will have if they are working non-stop for weeks on end.
This client thought he knew more than me about everything. He is a developer who sells plots with planning permission then he builds his customer's house re-arranging the internal layout to whatever they request.
But he has perimeter land drainage around his basement that doesn't drain.
He has a stairwell that will be open to the weather and rain falling in his stairwell needs to be pumped. But that would be a limited amount of water.
His pumping chamber should only be removing rain from his stairwell.
If his perimeter land drain doesn't drain he should not have a perimeter land drain. The basement should be waterproof and heavy enough not to float. That might require piles designed to resist being lifted up, rather than to take weight.
This pumping chamber is in front of basement patio doors in what will become a stair well.
Rain will filter between paving slabs on stools and find its way into a gully.
This image was taken in 2005. I didn't hear of any flooding but this was a builder extending his own home, so he probably thought he knew best as well.
It would be even worse if either of these sumps had been inside the basement.
This image appears on several of these pages as examples of work by others with many causes of basement leaks visible.
They added more duct before they tipped free draining shingle on top. I expect they split the joints and when it rains heavily water pours in to the pumping chamber from outside.
The pump will have too much work to do and from time to time it will burn out and need replacing.
Obviously it will only burn out when it is pumping water. The basement is likely to flood before they replace it.
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