As mentioned, it is just a holding tank. We have used Charmin for many years and have never had a problem. Of course the secret is use water. Even one ply will cause problems if not enough water is used. I also do not use any chemicals. I just flush with plain water using my black tank flush. I make sure my tank is at least 3/4 full. If not, I will put water in till it is 3/4 full.