Hi there, we are interested in buying a house but have been informed by the tenants who currently live there that Thames water had detected a leak somewhere on the property. According to the tenants the landlord has never resolved it and we don't know anymore details than that. There are no physical signs of a leak anywhere in the house. Potentially, how expensive could the worst case scenario of an untreated leak be? We are hesitant to reveal to the seller that we know this information and ask further about it as the tenants told us in confidence.