Help designing a water wall or weeping wall

May 28, 2008 4:02 PM

Hi, I am a contractor and have been assigned the task of building a "weeping wall" in the bathroom for our client. The wall will be a rock wall tilted to about 5 degrees for the water to run down. My question is in regards to the size of the pump and type of drip required to obtain the weeping wall objective.

The overall height the water will have to travel from the reservoir at the bottom to the delivery system at the top is about 10'. We are not looking for a torrent of water to be rushing down the wall, just a trickle of water down the rocky surface.

The second part of the question would be what would be the preferred method to deliver the water to the wall. I have heard of two different methods: 1) Supply a length of 1/2" copper pipe fed with water from both ends and drill small holes spaced every so often for the water to drip from. And 2) Same as above except instead of holes, cut a slot along the length of the pipe for the water to flow evenly from.

Thank you all for your time!

posted by Jackie_Treehorn to home & garden (15 comments total)

I am not a contractor, but I feel this is an important question -- is this wall to be just for decoration? Or will it be some sort of trough urinal?
posted by Zephyrial at 4:07 PM on May 28

yow, if my contractor was asking mefi how to do a job on my house i'd be pretty freaked out! perhaps you should talk to your boss before moving forward!
posted by Salvatorparadise at 4:22 PM on May 28 [1 favorite]

Sounds like a fun project. I've never done this, but here's how I'd approach it:

Direct the fine mist from a hose nozzle and at a mocked-up section of stone wall, adjusting the flow rate until the trickle looks about right, then measure that flow rate (how many seconds to fill a gallon jug, or something like that), and adjust for the difference between the size of the actual wall and the size of your test area. Use that result to choose a pump. Plumb the pump to a scrap piece of pipe hung horizontally, 10' above. Keep drilling small holes in the horizontal pipe until the holes drip rather than spray. Count the number of holes you drilled, and space that number of holes evenly along the length of the pipe you actually install in the wall.
posted by jon1270 at 4:31 PM on May 28 [2 favorites]

Well hmmm, I was just working on my drip system in the front yard and it seems to me you could go with a pretty basic low pressure set up with conventional drip heads, easily serviceable to boot.

This seems to be a closed system, so maybe this would work as your pump with a couple of conventional rainbird/etc heads on the system. Max lift is 12.2 ft.

You'll probably have to play with this a bit, I think your biggest trouble will be lifting power vs volume lifted. So if you find you are lifting too large a volume and you decrease the power of the pump or go with a smaller pump you might end up without enough go juice going to pump to hit the minimum lift height. In that case you're probably better off going with a system that will left as needed to a holding tank at the top of the system and let it gravity feed on to the wall.
posted by iamabot at 4:34 PM on May 28

Also, I'd incorporate a fine-mesh filter (cheap ones are available from drip irrigation companies) to prevent debris from clogging the holes.
posted by jon1270 at 4:34 PM on May 28

isn't this the sort of thing that people pay to avoid having happen to them?

in that vein, i would worry about the hygiene aspects of a closed system. between the mold annd the dust/hair i'd imagine you would at least want a filter and would still imagine the wall would get slimy pretty quick. maybe you should incorporate some kind of uv lighting to keep the microorganisms at bay...
posted by geos at 4:53 PM on May 28

I'd make a shallow trough along the length of the top of the wall and discharge the pump into it. That way when it spills over you'll get water over the entire length of the wall, not just in one spot.
posted by electroboy at 4:56 PM on May 28 [1 favorite]

Yeah, adding to what geos said, there's going to be mold and mildew like crazy without some sort of dehumidication/ventilation... but hey, whatever the customer wants.
posted by mr. creosote at 5:32 PM on May 28

Aquarium filters and aeration will help keep the reservoir from getting funky.
posted by hortense at 7:15 PM on May 28 [1 favorite]

I once worked on a similar project for a restaurant. It was a five degree wall of water, but it was flat. There were constant problems, and it was shut down for good in less than a year because everybody was sick of wrangling with it.

Basically, the water will congeal, within a couple feet from the top, into several streams of its own choosing, and will stubbornly stick to these paths. We tried putting different coatings on the wall, but it was futile. Adding surface tension breaker (like soap) was futile. Increasing the flow caused too much spattering and a wet floor, or, wetter, since it was spattering already. Trying to devise variable outflows at the top was futile (it still returned to its paths).

I suppose, since your wall won't be flat, that the, uh, visual monotony of the static paths will be disguised. But if can find a way to, check what the water does before finalizing the contours of the wall. And definitely before installing it on site! Because what that water does is what it will do for all time.

Since my experience on that job, I've paid more attention to similar fancy water-projects, like you see in malls or restaurants, and I've noticed that they're always shut down before long, even when they work properly. Well, for what that's worth... I suppose maintenance won't be your concern.
posted by Rich Smorgasbord at 7:20 PM on May 28 [1 favorite]

With the previously mentioned small well behind the feature, a working, maintained and hopefully bio-type filter and water conditioning regimen this should work for some time. If you also incorporate a magnetic-driven pump it's also cheap (~300 gph @ 5 ft. head 24/7 = $3/mo.) You've got to keep up on either chlorine or bio-bacteria and filter cleaning. If outdoors, even more so. Way back when, I used to work here for a great boss...
posted by prodevel at 11:06 PM on May 28

Zephyrial - the wall is purely for decoration. Kinda Zen feeling I think.

Salvatorparadise - At least THIS contractor is asking the questions! Many would just do the best he knew how, collect the check and move on. That is not how we operate. Knowledge is power and I am obtaining as much of it as I can. Thanks.

The bio issue is an interesting one and something we had not considered. We will make sure to take the appropriate steps to control that. Also, the fine mesh filter for keeping small debris out of the tiny holes is helpful as well.

It will be months until we are finished, but I will post a linky to some photos of the finish product.

Thank you!
posted by Jackie_Treehorn at 5:03 AM on May 29

mr. creosote - we are planning to control the humidity created with this system via a humidity sensing exhaust fan. It kicks in and shuts off automatically to control the moisture in the room.
posted by Jackie_Treehorn at 5:17 AM on May 29

Google '"spray booth" water wall'. In the spraying industry they use water walls to pick up paint particles from the air.
posted by oliverst at 3:18 AM on May 31

There is bound to be a pond supply store near you. They could offer more suggestions for keeping the pond clean and hassle free than you can get here. Google for pond forums; someone has already done this, you know they have.

Many pumps will tell you quite clearly how many gph at what lift. The suggestion that you do an actual pour, say, a gallon bucket spilled over your wall over a minute will give you some idea as to what range you want your pump to be in.

I have bought small pumps from fountain mountain that have worked fine. In my outdoor pond I am using a pondmaster pump that handles the algae better than some. Hopefully that will not be an issue for your clients. I would call and ask what the pump curve shows at your 10' head height for different pumps.

If you buy a pump that has excess capacity you can control the flow by creating a "T" where one arm goes up your wall and the other to a valve that can send flow directly back to the reservoir.

If it were my wall I would not be bothered if it was not uniformly wet. If your client expects this it maynever be a problem.

Hinted at but not spelled out- pay attention to the watts. There are pumps that use alot more/less electricity than others.

It sounds like an interesting project. I hope you enjoy yourself.
posted by pointilist at 5:33 PM on June 2