water proofing of water tank

I am facing problem to making underground water tank as water is coming continuously. we have constructed 4" outer brick wall except joining joint of bottom brick wall from all four side so that all water only  come through open  joint of  bottom of wall .like this way we have constucted wall up to desire level.

Now problem  is as we go to drain all water through pump for joining that remaining open joint of wall, water is continuously coming and we are unable to do plaster or joint that open joint

is there any solution for this?

Thanks