Forum Discussion

Atlee's avatar
Atlee
Explorer II
Feb 22, 2018

By passed Black Tank Flush back flow preventer

The back flow preventer failed after 5 months of use. Was going to replace it yesterday, but @ $50, I decided no. Looked for a simple plastic elbow, but couldn't find one, so made a brass one. Also used a couple of strap hangers to help secure the flush tubing. Something that should have been done at the factory, IMO.




The broken piece is on the left. $50 The two brass pieces used to replace it are on the right. $13.15




I added strap hangers to help keep the top heavy long run of plastic pipe in one place.

61 Replies

  • It doesn't have to cost $50 for the cheap plastic one ..go to Lowes Under $19 for a brass one, of course you'll need two 1/2" nipples. The system should function as designed without the horrible adverse effect inside your fresh water system.

About DIY Maintenance

RV projects you can tackle on your own with a few friendly pointers.4,382 PostsLatest Activity: Jul 26, 2025