Systems: Water Pipe Dump

There will be times when we need to leave the house unoccupied. During those times I'd rather not worry about pipes freezing. During the winter of 2003-2004 many houses on the island had just that problem. Water leaks went undetected for weeks and there were stories of lost carpets, furniture and in one case I heard, an entire 3-story staircase was damaged beyond repair.

Why does this happen? Well, absentee island property owners sometimes fail to appreciate how cold it gets in the months when no one is going to the beach. The temperature can drop to zero degrees F. Combine that with 50 mph winds and building codes that require flood vents in the lower level, and we have a problem.

Our solution is to shut down and drain the entire plumbing system any time we leave the house in the winter. To facilitate this, we have used two ball valves at the bottom of the system. These valves can be opened or closed with a 90-degree flip of the levers. Closing the supply valve and opening the single drain valve dumps all of the water in the pipes. This works only if all the pipes are properly sloped toward the supply/dump pipe, which they should be in any case. Also, some of the fixtures' supply valves need to be cracked open to break the vacuum when draining.

I have replaced globe and gate valves with ball valves in other plumbing projects and have lived happily with them. The cost premium for ball valves is minimal and the speed advantages are great. Big, clear, waterproof labels are also very helpful in an emergency.

As shown in the photo above, the water main entry is brought up through the sand under the house. A utility box is put over the supply pipe prior to pouring the concrete slab.

Once the slab is poured up to the utility box, it provides both the entry and the exit for water in the pipes. The dumped water just goes into the box and, owing to the very rapid draining of the water through the sand, it is gone. I've tested it and it works. I can drain the whole house in a few minutes.

For a more extended, totally-unheated house situation, things like water in toilet tanks and the washing machine need to be dealt with separately.