The A.O. Smith AO-MF-ADV is an under-the-sink purifier which filters water directly from your existing faucet. This drinking water filter reduces up to 99% of 77 harmful contaminants including chlorine, chloramine, lead, mercury, BPA, PFOA/PFOS and cysts. It also improves the turbidity of the water. The water is filtered by four filtration methods but nothing is added to your water during the filtration process. If you have more than four people in your household then this is perfect for you!