Just curious? Do you wash dishes in your sink? More important, do you wash your pots and pans and skillets in the sink? Even more important, if those pots and pans have grease on them, do you let that grease go down the drain? If so, your pipes could be clogged due to grease.
Don't know about you, but we use our sink mostly for just water and wash dishes outside. But between trips, there's no water going down the drain. This allows food particles (and especially grease) to dry, get hard, and stick to the sides and bottom of the pipes.
I suggest you go to Lowe's or Home Depot or your local Hardware store and get a drain emzine eater. It's usually in a powder form, you mix with warm water and pour down your drains. This is the same type of stuff used on cruise ships, high rise apartments, and in your home.
If the clog or slow drain is due to any bio-degradable object, the emzine eaters will dissolve whatever the problem is (organic objects). It will not eat up plastic or metal, or non-organic items). It will dissolve hair.
And No! This will not hurt your pipes. If it would, then every pipe in my house would be destroyed, as everything is PVC. Your camper is also PVC.
This is what we use. We've purchased it through our plumber, but Lowes,etc also sells other brands (a lot cheaper) that do the same thing.
Click here.It's important to keep the drain wet. So once you make up a cup of the solution, pour it down your drain and let it sit for the specified time (12 hours), then run water down the drain. In order for the emzines to continue working, they have to be kept wet. Unlike your home where you use water all the time, you'll need to keep putting a little bit of water down your sink often for a few days. Once ,the emzines have eaten everything, the pipes are clean and the emzine die because there's nothing left to feed on. Also, they will get in your gray water tank and clean it up too! So you've got nothing to loose.
Try it. See if that works!
Edit! We never put grease or food particles down our trailer sink drain. When we do have to wash inside, we wipe the greasy dishes with paper towel first and toss the paper out. This greatly reduces the amount of grease going down the drain, and for that small amount, normal dishwashing soap will keep it broken down and flushed out. We do the same thing at home, especially since we are on a septic tank. We use the Bio-Clean once a month, one cap full for 1 glass of warm water, 1 for every drain in the house. We've never had a clog. I started using it in the camper too now, especially since our camper is still less than 1 year old. I figure, it won't hurt to start prevention! Worst case scenario! Those emzines float into the gray tank. It's always a little wet!
