The best prices on the best RV toilets in the Industry. Many customers now replace their older plastic RV toilet (that came with their RV) with the newer porcelain toilets. Porcelain RV toilets have a residential look and feel. Both Thetford & Dometic toilets will interchange with each other and these newer models are much more water efficient. Both Thetford & Dometic still offer plastic toilets that perform great and are an excellent value. Here’s a quick video on RV toilet replacement.