How much does a water pressure reducing valve installation cost in Los Angeles? The cost to replace and install a water pressure regulating valve in Los Angeles ranges from $450 to $875 (parts and labor) depending on the regulator’s size. For example, a good quality 3/4″ pressure reducing valve costs between $100 to $150. Larger sizes cost more. If homeowners are unsure if they need a replacement, we can perform a water pressure reducing valve inspection. If we determine there is no need to repair or replace the valve, our fee is $70.