I have never had to replace mine in any of my rv's. But having said that I have had to clean them as they sometimes get buildup on them and prevents them from sealing. If you have to replace your's that often I guess I would ask if you use some type of regular toilet cleaner that may damage the seal. Or maybe your's also just suffers from buildup and you are prematurely replacing them. To clean them I just put on some rubber gloves  and use a piece of sos pad and just rub the sealing surfaces. If I remember right the sealand has the half ball shape. That is currently what we have installed (I just put it in a couple of months ago). What i took out was probably the Tetford which has the slide type seal. On the Tetford the seal is a bit harder and that was the one I would use the sos pad on. The dometic is a fairly soft seal and they are easy to replace so I would not pay someone to do it for you if you don't mind doing your own maintenance. Once you remove the bottom cover there will be some type of clamp or screws. Mine which is a 510 model is nothing more than a huge worm hose clamp. Should only take about 15 minutes to replace.

Since my husband just had to do this to our RV its a 2002 fiver and he did it himself as he usually can do most of anything that we need done.  We dont know when it was done last but it just wasnt holding the water like it should.

southwestjudy & Bob & 2blackdogs

Hi Judy,

If that is the Sealand Traveler, the porcelain unit, I would think yearly is too often. I replaced ours only once in 4 years. If it leaks, the docs say to tighten the screws on occasion. Too pricey for more often than that.

Mike