Wow! Lots of good input from you folks. I have been using the filter shown in Gdetrailer's photo. I used this cheap filter from Walmart for years with no problem, but them I always had it installed outside. I didn't think of the water heater pressure. Sounds like my filter became the weak link. I originally tried a hookup that looks like the the one in JFrampey's photo. I bought the Hydro Life Model HL200 from Camping World. I liked the filter specs, but the garden hose fittings always leaked after installing it inside, under the sink. I think I know why now--too much pressure. Now that spring is here I will be installing it outside where it belongs. Hey. I learned something. Thanks again for all the ideas.