Basement wall leaks are always a serious issue. This is because seeping water degrades the strength of your foundation, and allows mold and mildew to propagate. In order to fix the leak, you must locate the source. Tracing the water back to where it emerges is always a good starting point. When you’ve found the source, use a hammer and chisel to carefully open any cracks or voids and inspect them for extensive damage. The cracks that are visible are not the extent of the damage, so if you just cover them you will have future problems. Once you’ve checked the cracks for further damage, use a brush to rid the crack of loose debris. Once you think you’ve gotten it all, use a can of compressed air to finish the tidy-up. Next, mix some hydraulic cement and apply the mixture to the crack, assuring that you press as far as you can. You can also use small pieces of stone or already hardened cement to help fill this gap. Once you have sealed the cracks, apply a waterproof sealant to protect against any future damages. This method is the most widely accepted. Another solution, besides concrete, exists in the form of epoxy crack injection. Mar-flex sells these epoxy sealant kits.