Finally got to the bottom of a water leak in my house today -- one of the toilets had a very slow leak and has been constantly running for estimated last 12 months. Only found out by chance when I called water board to try and see if we could save any money - they told us our water usage was very high! Anyway, took about 3 weeks to pinpoint the leak. I worked out that over the last 12 months we have lost roughly 100,000 litres of water as a result of this leak! And it's cost us around £400-£500! (no it's no relation to IM, just me happy to have solved a big problem!!!).