We have well water that contains some minerals, but is not normally a problem. I use a Vicks UV 99.9% Germ Free Mist Humidifier in my bedroom. It holds 2 gallons and we are putting 2 gallons into the air every 24 hours during dry winter weather. This pad needs to be cut down slightly to fit properly. I use it for 5-7 nights before replacing it and there is still some mineral sediment that collects under the pad. However,I can see that it does help to contain much of the mineral content. I ran out and used my humidifier without the pads for a couple of nights and I could definitely see many more mineral deposits throughout the base of the unit. I expect it will extend the life of my humidifier and I will continue to use them regularly. I found that they are hard to find and Amazon was the best solution to purchase these pads.