Sump pits collect water and other fluids. Most are located in the basement, pumping out water to avoid flooding. Bricks or concrete line the pit walls, and it is on this surface that detergent, soap residue and algae collect. A sump pump removes the liquid from the pit so it does not become too full. Sump pits are not only for home use. They are in places such as hospitals or car repair shops where they collect a variety of liquids. Clean your sump pit periodically to keep foul smells to a minimum.
Remove the cover of the pit. Disconnect the sump pump from the electrical outlet and remove it from the pit, or leave it in so it can pump the gunk out.
Spray the walls and bottom of the sump pit with a garden hose. The pump will do its job and pump the gunk away. If your garden hose won't reach, scrape and scoop the crud from the walls.
Keep spraying until the water is clear.
Clean the walls of the pit with bleach and a scrub brush. Use as much bleach as you need to get the job done. This sanitizes the pit and slows the sour smell from returning.
Mix the bleach to a ratio of 1 oz. to a cup of water. Pour the mixture into a spray bottle and spray the walls of the pit as you scrub. You can scoop the gunk into a bucket, or use your wet-vac and suck it up if you have disconnected the pump.
Add 1 to 2 tbsp.of oil in the sump pump crock. The oil helps seal it so the smell will not come through.