Water Cut-off For centuries, builders have fought against the Inflow and infiltration of water into their structures. Even today, most modern infrastructure is sensitive to the inflow of water, including manholes, concrete vaults, basement levels and sewer lines. The repair process involves the injection of an expanding polymer upstream from the problem area. In it’s liquid form, the low viscosity grout will enter the system and follow the same path as water. Within seconds, the grout rapidly expands and then starts to cut-off the pathway for water flow. When done properly, a majority of the flow of water can be cut off within minutes of starting the process.