Contamination to check for leaks

Water supplies can be contaminated with a gamma-emitting radioactive isotope to find leaks in pipes . Where there is a leak, contaminated water seeps into the ground, causing a build-up of gamma emissions in that area which can be found using a Geiger-Muller tube. This makes it easier to decide where to dig to find the leak Isotopes chosen must: - Emit gamma - have a half-life of at least several days to allow the emissions to build up in the soil - not be poisonous to humans as it will form part of the water supply