In the letter that many Councils now send to households that have failed their compulsory water test, the EHO’s (Environmental Health Officers) include the following paragraph “Enforcement action may be taken where the (Private Water Supply) Regulations are breached. We also alert prospective purchasers during searches prior to buying property to any danger or lack of serviced treatment equipment”. So yes, the price of your property will be affected if you don’t do something about your water.