Bathroom Dry Pipe
First of all I want to thank everyone here for several years of entertainment, education, and ideas gained from reading this forum. Although I rarely post, I look forward to visiting the website several times a week.
Here is an addition that has made the draining and flushing of my 5th-wheeler’s black-water tank quite a bit easier. I installed a dry pipe in the bathroom right next to the commode. It is used to fill the tank with additional water just prior to dumping, and to add 5 gallons or so to the emptied tank to prevent the dreaded “poo pyramid” before the next dump (no pun intended). The pipe is “dry” since it is only charged with water when the black tank is emptied.
I used ½” sch.40 PVC pipe to run a line from near the dump connection on the street side, across the underbelly, then up into the bathroom next to the commode where a ½” FPT brass quarter-turn hose bibb controls water flow. The street-side end of the pipe has a ¾” female hose fitting to which my utility hose is connected. In use, a short length of ½” I.D. vinyl tubing is attached to the bibb and pointed straight down the toilet’s open waste valve to add water to the black tank. The tubing must be hand-held during this operation to prevent overfilling of the tank. Mine also has enough curl to it to prevent it from staying in the toilet and thereby eliminating the possibility of a cross-connection with fresh and waste water. When finished the utility hose is stowed and water in the pipe is allowed to drain out for a few moments, the FHT connection is plugged, the bibb is capped (even though it is unnecessary), and the vinyl tubing is put into a large ziplock bag and stored behind the commode. The vinyl has never gotten dirty so I have no qualms about storing it this way.
One caution – after pressurizing the pipe, be very careful opening the quarter-turn valve to fill the black tank. The line will have air in it and can splash water in the commode which can then land in places where it doesn’t belong. Guess how I found this out. In addition, since my utility hose is also used for the tank flusher, I put a hose-end ball valve with a quick-connect fitting between the utility hose and the dry pipe inlet. When a hose switch is needed, I just turn off the ball valve to keep the line full of water, then attach the hose to the tank flush inlet via a brass 90-degree ell which is also equipped with a quick-connect fitting. A reconnect to the dry pipe will let a small amount of air back into the line but I can usually hear it coming through the pipe and close the valve a bit to eliminate splashing.
Here are some pictures that should make things more understandable than my poor efforts at written explanation. I didn't like having to make multiple trips with a 5-gallon water bottle to put in the toilet prior to having to dump a short-filled tank, nor dragging a long hose inside to do the job. Perhaps someone else can benefit from this idea.
Hole in the floor for 1/2" PVC pipe.
Detail showing homemade drop-ear ell, bibb and cap holder
Sprayed with satin finish black paint for plastic. The white cap is screwed to a 3/4"MHT x 1/2"MPT connector and used to just keep crud out of the line when not in use.
Here is an addition that has made the draining and flushing of my 5th-wheeler’s black-water tank quite a bit easier. I installed a dry pipe in the bathroom right next to the commode. It is used to fill the tank with additional water just prior to dumping, and to add 5 gallons or so to the emptied tank to prevent the dreaded “poo pyramid” before the next dump (no pun intended). The pipe is “dry” since it is only charged with water when the black tank is emptied.
I used ½” sch.40 PVC pipe to run a line from near the dump connection on the street side, across the underbelly, then up into the bathroom next to the commode where a ½” FPT brass quarter-turn hose bibb controls water flow. The street-side end of the pipe has a ¾” female hose fitting to which my utility hose is connected. In use, a short length of ½” I.D. vinyl tubing is attached to the bibb and pointed straight down the toilet’s open waste valve to add water to the black tank. The tubing must be hand-held during this operation to prevent overfilling of the tank. Mine also has enough curl to it to prevent it from staying in the toilet and thereby eliminating the possibility of a cross-connection with fresh and waste water. When finished the utility hose is stowed and water in the pipe is allowed to drain out for a few moments, the FHT connection is plugged, the bibb is capped (even though it is unnecessary), and the vinyl tubing is put into a large ziplock bag and stored behind the commode. The vinyl has never gotten dirty so I have no qualms about storing it this way.
One caution – after pressurizing the pipe, be very careful opening the quarter-turn valve to fill the black tank. The line will have air in it and can splash water in the commode which can then land in places where it doesn’t belong. Guess how I found this out. In addition, since my utility hose is also used for the tank flusher, I put a hose-end ball valve with a quick-connect fitting between the utility hose and the dry pipe inlet. When a hose switch is needed, I just turn off the ball valve to keep the line full of water, then attach the hose to the tank flush inlet via a brass 90-degree ell which is also equipped with a quick-connect fitting. A reconnect to the dry pipe will let a small amount of air back into the line but I can usually hear it coming through the pipe and close the valve a bit to eliminate splashing.
Here are some pictures that should make things more understandable than my poor efforts at written explanation. I didn't like having to make multiple trips with a 5-gallon water bottle to put in the toilet prior to having to dump a short-filled tank, nor dragging a long hose inside to do the job. Perhaps someone else can benefit from this idea.
Hole in the floor for 1/2" PVC pipe.
Detail showing homemade drop-ear ell, bibb and cap holder
Sprayed with satin finish black paint for plastic. The white cap is screwed to a 3/4"MHT x 1/2"MPT connector and used to just keep crud out of the line when not in use.
