This is not something unreasonable for them to have as a concern. For example, city water companies in many instances have their own well, which they test for water quality. (always debatable though, to me) When we were on city water (as opposed to being on our own lovely well, now) we had strong communications from the water company that, being in an agricultural area with livestock water tanks etc which were filled with hoses, to be extremely careful about backwash from hoses from the livestock tanks - when the water was turned off at the faucet the hose HAD to already be outside of the water tank, because, the hose would after a few moments of being turned off, reverse the water flow back in the city system. Weird~but there were a couple times when this exact kind of bacterial issue ("bad water") contaminated the city water.

This is not something unreasonable for them to have as a concern. For example, city water companies in many instances have their own well, which they test for water quality. (always debatable though, to me) When we were on city water (as opposed to being on our own lovely well, now) we had strong communications from the water company that, being in an agricultural area with livestock water tanks etc which were filled with hoses, to be extremely careful about backwash from hoses in livestock tanks - when the water was turned off at the faucet the hose HAD to already be outside of the water tank, because, the hose would after a few moments of being turned off, reverse the water flow back in the city system. Weird~but there were a couple times when this exact kind of bacterial issue ("bad water") contaminated the city water.

This is not something unreasonable for them to have as a concern. For example, city water companies in many instances have their own well, which they test for water quality. (always debatable though, to me) When we were on city water (as opposed to being on our own lovely well, now) we had strong communications from the water company that, being in an agricultural area with livestock water tanks etc which were filled with by hoses, to be extremely careful about backwash from hoses in livestock tanks - when the water was turned off at the faucet the hose HAD to already be outside of the water tank, because, the hose would after a few moments of being turned off, reverse the water flow back in the city system. Weird~but there were a couple times when this exact kind of bacterial issue ("bad water") contaminated the city water.