Remember this? It’s Gypsy’s old p-trap. I hacked it together from a branched tailpiece and an air gap cap … in 2013. (Seriously? I’ve been working on this van for that long? This must be a record.)
My hack worked fine for 2 years, and then it started to drain veeeeeeery slowly. It was a pain because a pool of water would gather in the bowl of the sink and splash back at me whenever I used the faucet. It was gross. I decided to switch it out with something better. But what?
Well, after Jef bought Wanda the Westy, he changed Wanda’s p-trap, and I noticed his replacement part looked like the exact kind of thing I needed two years ago.
To make a long story short, I bought one to see if it might work and … it worked!
Well, I kind of had to force it to work. But it does work.
The issue is that this p-trap is made for a VW Vanagon. VWs are European, and Europeans use the metric system (cue Pulp Fiction moment). So, best I can tell, this VW p-trap is sized for sink strainers that are 40 mm (just a hair larger than 1.5”) and exit hoses that are 16 mm (just a hair larger than 5/8”).
The solution was actually pretty easy. I was able to stretch my 5/8” hose (goes from the sink to the grey water tank) onto the new p-trap barb by heating it with a heat gun. As for attaching the p-trap to the sink strainer, I first attached a brass adapter ring (originally meant for attaching garbage disposals) to the sink strainer, then wrapped the adapter ring threads with Rescue Tape (to increase the diameter to fit the p-trap), and finally mounted the p-trap over the Rescue Tape. It works great!
So, what have we learned from this? Well, if you’re looking to plumb a standard American sink to a DIY grey water tank, here’s one way to do it (I’m only telling you this because there is surprisingly little information out there about what connects to what):
- Use a sink that has a hole in the bottom for a 3.5″ sink strainer
- Install a standard household 3.5″ sink strainer
- You might need to attach a brass garbage disposal adapter ring from the orange box store (it has deeper threads, which will catch better on the threads of the p-trap)
- Wrap the adapter ring threads with Rescue Tape
- Screw on a p-trap from gowesty.com
- Attach a 5/8” (inner diameter) braided hose to the barb coming out of the p-trap (heat it up a little to stretch around the barb). Use a hose clamp to secure it over the barb.
- Install the fittings from a Todd Marine Relocation Kit on a grey water tank of your choice. One of the 5/8″ thru hull fittings will be the inlet. The other 5/8″ fitting will be for the drain (attach 5/8″ hose, then 5/8″ to 1/2″ barb reducer, then 1/2″ PEX pipe, then 1/2″ flair-it stop valve).
- Attach the free end of the 5/8” braided hose to the 5/8” thru hull fitting serving as an inlet to the grey water tank. Use a hose clamp to secure it.
Easy peasy. Only took me 2 years to figure it out. Keep in mind that this isn’t the only way to do it. This is how I did it because that is what fulfilled my needs at the time. What fulfills your needs may be totally different. And hey, figuring out new ways to do things is part of the fun, right?
By the way, part of the “long story” that I skipped over involved trying to find a new sink strainer to fit the new metric-sized p-trap. The only one I could find was made of flimsy plastic. While I was skeptical that it would hold up, I decided to give it a try anyway.
It held up fine … for two days. And then it completely broke.
Boo. Metal for sink strainers. Always go with metal.