OT: Irrigation System Help

Hey all. I've recently installed a nice big rain collection system, and have run into a small issue I hope to solve easily.

Basically, the rain barrel is connected to a pump that in turn feeds a hose manifold, and I have a bunch of hoses that go to various gardens.

The problem is that the rain barrel is located at a point higher than the gardens, and I'm getting gravity flow-through when the pump is off. When I look at anti-siphon valves, they are (apparently) not what I need - they are for preventing backflow into the water supply, I want to prevent low-flow forward into the system, which drains the tank, floods the garden and so on.

I've looked at check valves with adjustable cracking pressure, that's not quite what I need. Can someone tell me what to search for? I want a valve that only opens when the inward pressure is above 2 or 3 psi (ideally adjustable).

What is that thing I need called?

How about looking for a solenoid valve and wiring it to come on with the pump. Power up the pump and the valve opens, shut off the pump and the valve closes.

- Eric

I assume this is an automated watering system (on a timer)?

I wonder if it would be simpler to add a loop on the pump outlet that stands above the water line in the tank. End of siphoning problem.

Think what you are looking for is a vacuum breaker. But it has been a long time since I sold hardware so I might be wrong. Do you have a plumbing supply or irrigation supply company nearby? Usually the help at a business that supplies other businesses have help that are more knowledgeable than the big box type stores. If I were looking that's where I would start.

That is a common enough issue for water systems, and an easy enough issue to fix.

What you need is a loop of pipe raised above the maximum water level and a anti-siphon valve installed at the high point. This should be located on the discharge side of the pump.

If you want to save a little money it is simple enough to avoid having to buy an anti-siphon valve and simply drill a tiny hole in the top of the loop. The hole only has to be big enough to allow air in and you can get creative with the tiny fountain coming off the top of the loop when the pump runs.

An interesting variation is to install hose barb at the top instead of just having a hole. From there you run a bit of vinyl hose to something that needs watering. Or even just back to the tank. If you do use some tubing you will have to make sure it drains by gravity without any bellies or obstructions so it will allow the air to flow back up and break the vacuum on the loop and stop the siphoning.

Pardon my poorly-thought-out reply above . A higher-than-source loop alone will not help; it must be combined with some sort of air intake into the piping to break the siphon effect. So, a valve that closes under pump pressure but opens to admit air under siphon (slight vacuum). But that doesn't give you a name.

EDIT: Art beat me to it.

Wouldn't it just be easier to put a hose spigot on the manifold and shut it off when you don't need it? Then treat it like a regular hose outlet.

What you're looking for is something similar to a pressure relief valve, but I imagine those aren't really designed for that kind of application and would restrict the flow quite a bit.

That's the solution! I will pop a 1/8" hole in the discharge line, run a bit of tubing back to the tank, and that will solve the problem easily. Thanks Art.

Art, that idea worked like a charm. I put a t fitting in and a small return line after a check valve that holds the prime in the pump and connected a 1/4" tube from the t up to the tank. A small amount of water flows back into the tank, and when I shut down the pump, the line quickly breaks the siphon - problem solved...now on to the timer switch and to find another 350 gallon tank to sit next to the first one (which I found being thrown out - it was a brine tank for a school water softener and they had let the salt harden into a single 500 lb block, but I was able to get the salt out by cutting it with a pressure washer set to 0 degrees)

No way! Did you save any of the salt =D? Would be a great resource for The end of the world so you could cure meats =P

If your willing to wing it a little tanks are not a big problem.

One of the easiest, and most cost-effective, is to head down to the discount store and get a kiddie pool or two. A 6' diameter kiddie pool 12" deep holds about 200 gallons.

While there pick up some nylon scrim from the fabrics section and a large rubber ball. Drape the scrim over it and use the rubber ball to keep it above the water so bugs don't take up housekeeping.

I've seen someone mount kiddie pols rim-to-rim to make an nice tank. The key was arranging a piece of PVC pipe under both rims and screwing/bolting it together every few inches. I helped them bend the pipe. They used a urethane adhesive caulk after cleaning the plastic surfaces vigorously. Stacked you get about 400 gallons but joining struck me a lot of trouble to get the same capacity as two siting side-by-side.

Another alternative is to use 2bys joined at the ends with cheap galvanized steel angles to form a frame sitting on the ground. This can then be lined with sheep plastic to form a tank. If you can a safety liner intended for a waterbed you get pretty corners.

The main bladder for a waterbed will also work but bladders can be tricky. Sealed you avoid insects and contamination. Flexible they don't form vacuum. But cleaning and inspecting can be problematic.

Sheet polyethylene will work for simple open-frame tanks but exposure to sunlight degrades it. The black last longer in sunlight but all of it is pretty long lived if kept in the shade. It comes in various thicknesses. Thinner is cheaper but more prone to puncture.

Even simpler, but more labor, is to simply dig a hole and line it to create a pond. Most home centers will sell you a 'pond liner' which is heavy, typically black, PVC.

I would advise that if you try plastic lined tanks start with cheap Visqueen, sheet plastic, to assemble the project and get it all up and running. If you are still pleased with the design after a few months you can reline it with the more expensive liner materials.

The "salt" was actually some kind of potassium that's supposedly safer than the salt. I tossed it.

Can you post a picture of this? I'm having difficulting figuring out what this device looks like and if it would work with my rainwater harvesting system.
Thanks,
-Blast

Here's a really bad drawing:


In written out terms, starting from in the tank.

At the start of the system is a foot valve (keeps the water in the pipe) that's connected to 1" plastic piping with up and out of the tank and down to the pump, which is at ground level. I didn't want to pop a hole into the tank, so the up and over method was used.

The pump has 1" piping, at the discharge, I put in a check valve so that the water can only flow out of the pump. With a small nipple fitting, I then attached a 1" "T" fitting. The left side of the T fitting was fitted with a reducing bushing to get me to a 1/4" NPT female threads into which I placed one of these.

From that barb fitting, I ran 1/4" tubing back up and into the tank.

The other side of the "T" fitting connected to the existing 4 outlet hose manifold I had built some time ago. It's a simple array of hose bibs along a piece of copper tubing that I had found in the basement. Each is sweat-fitted.

When I run the pump, a small amount of water flows up the 1/4" tubing and back into the tank. This has almost no effect on the overall flow through the system, and actually serves as a "bypass mode" for the pump in the event that all of the hose bibs are closed, so it can actually extend the system life.

When I shut down the pump, the check valve on the pump closes, holding prime in the pump, and then air is drawn back into the 1/4" tubing, breaking the siphon quickly. Obviously, the end of the 1/4" tubing needs to be held above the water line at all times, otherwise it will just be a second path for the water siphon.

Total cost in materials was under $50 (not counting the pump, which cost about $300 - it's a commercial grade, continuous duty device.

With the system I have in place, I have 350 gallons of rainwater that is collected, it's amazing how little rainfall you need to fill that barrel.

I also have will over 250,000 gallons of water in my pond, which would not require ANY storage tanks, siphon breakers or much else, but I prefer to not use that for garden irrigation due to the preponderance of tiny squiggly wiggly things in that water and I'd rather not spray them onto my Strawberries and Lettuce!

Thanks, I get it now. Nice and simple. My rainwater system is all gravity-fed, no pumps are used. Currently it consists of six 55-gal plastic drums (four plumbed together and two independent) with soaker hoses running through the garden beds. I have to manually turn on and off the water flow. I've forgot on occasion and drained all my water.
I was hoping the thing you and Art were describing would prevent that but I guess not.

-Blast

Blast, this is rough drawing of what I'm talking about.

The loop rises above the maximum water level and it alone, where it not for the unintended creation of a siphon, would stop all flow away from the tank through the pump. The addition of a vacuum-break, a tiny hole or valve they opens when the pressure goes negative, prevents the creation of the siphon. The loop and vacuum break work together to prevent all flow once the pump is turned off.

If you go with a small hole it only needs to be big enough to allow in air and to not clog. A 1/16", or even smaller, will usually work as long as the water is not too chunky.

Some people advocate inserting a thin copper wire into the vent hole. This is bent to keep it from being drawn in or blown out and extends a bit into the water flow so it wiggles and vibrates when the pump is pushing water past. The vibrating wire tends to keep the hole from clogging up from fine particulates or calcium.

Alas, that system requires a pump, which I don't have.
Turns out I left one of the spigots open on my system last night and ended up draining the four hooked-up barrels. D'oh!!

-Blast

Blast - sorry

Sounds like what you need is a watering timer. These are small self-contained, battery operated, solenoid valves that are activated by a digital timer. These can often be set up to activate for a established watering time on certain days of the week. I've never had one but a neighbor ran one for years.

It was a smallish unit that screwed onto the hose-bib that took a nine volt battery to operate.

There is also a simple mechanical one that allows you to manually turn the water on and set the valve to close in some number of minutes. The one I saw allowed a run time of up to four hours. This is essentially an egg timer that works a valve to turn off the valve when it goes off so you don't have to remember , or bother, to turn off the water.

Most hardware stores have them and they run $15 for the mechanical unit and $40 and up for the electronic one.

Ok guys, here's the system that I ended up building. Works great. I did away with the return tube.

Overview:


Detail:

Nice setup, Martin. Glad it's working well.

Though I wonder if such a perfectly utilitarian setup is really appropriate for Blast, our resident mad scientist. His system should have an infusion of Rube Goldberg elegance. Consider the materials at hand: water, a garden in containers, and a cat; wild plants, paracord, and things that go boom; a house full of survival gear and a tolerant DW. Surely we can add some thoughtful suggestions as to the design?

I'll post pictures of my system on Sunday. I think y'all will like it.
-Blast

p.s. No way in hell I'm letting a cat near my rain harvesting system.

[quote=Blast No way in hell I'm letting a cat near my rain harvesting system. [/quote]

Now you have to post your cat-proofing system.

Now you have to post your cat-proofing system. [/quote]

The fact that the process contains water is (I suppose) a kind of "intrinsic safety." Though both cats and birds are drawn to the sound of dripping water, with unpredictable and volatile results.

As long as Blast can incorporate one of those "fake fluid-filled birds that bob up and down as if they were pecking seeds" (what the *&%! are they called?) as part of the vacuum breaker system, I will be satisfied. But seriously, ETS-ers, we must be able to come up with a more complex way to do a simple task ... !?

[quote=dougwalkabout But seriously, ETS-ers, we must be able to come up with a more complex way to do a simple task ... !? [/quote]

Of course we must! And hopefully use lots of recycled materials in ways they were never intended and for which they may not be suited!

Okay, here's my system.

Main tanks: Three 55-gal Greek pepper barrels and one 66-gal Pepsi concentrate barrel. My preflush is simply some 4" PVC that fills up first and then the following water flows into the Pepsi drum. I have to manually unscrew the plug at the end of this PVC tubing to drain the preflush. All these barrels are plumbed together so they fill at the same time. You can't see it in this picture but the rain water enters the barrel through a basket lined in mosquito netting. This fliter is easily removed for cleaning.

Rain1 by merriwether, on Flickr

Secondary 66-gal Pepsi concentrate barrels. These are hooked to side gutters on the house, though the first one handles a very large section of roof. I wish I had room for another there. Neither of these currently have preflush systems.

Rain2 by merriwether, on Flickr


Rain3 by merriwether, on Flickr

The barrels are all raised above the levels of the beds they serve so I can use gravity to deliver the water where I need it.

-Blast

Nice. Though I must note that the tops of the barrels would seem to be cat-friendly.

To make it all a little more self-maintaining it would be easy to screw the clean-out plug in finger tight, mark the bottom of it, drill a 3/23" hole near the edge insert a piece of #14 solid copper wire and use pliers to put sharp bends in both ends. You want the end sticking out to be a bit long.

The wire should just about fill the drilled hole so the first-flow storage is self-draining while maximizing water capture. When/if the drain hole gets plugged with sand and crud you can simple wiggle the wire sticking out to restore flow. After a while you will have to remove the plug to clear the mud and crud so it stays self-draining but not every time. In this case extra convenience translates into more utility.

I don't bother with a preflush, wonder if I should...hmmm

Marty, Blast:

What is the purpose of the pre-flush other then perhaps clearing debris?

Up here, rain barrels in a rain forest environment are scare to non-existent so this is an educational thread. We are presently looking at purchasing property in a much more arid locale and I could really see rain barrels being useful there.

My two cents: typically the first water washed / flushed from a catchment system / roof is loaded with settled dust, insects, bird poop, miscellaneaous organic material, and pollution particles that you do not want to drink. Rather than overburden and possibly clog a filtration system with the initial dirty water load, you let it drain or flush away for a while before the presumably cleaner water is captured.

Exactly. It reduces the effort of purification later on.
-Blast

Ok, I had thought the purpose of the water barrels would be for lawn, garden watering etc. I did not think that the water in the barrels would be for drinking. My main concern would be the leaching of the chemicals in the roofing materials such as the petro-chemicals used in most asphalt shingles. How would you filter this out and make the water safer for drinking?

The water is mainly for the plants and flushing toilets if needed. I have a Big Berkey water filter system that will supposedly take out most chemicals. I also have the ability to distill water.

-Blast

The preflush, for me, is to get the small crud out of the system to reduce the need to clean the foot valve, that's all. If I was going to use rainwater for a drinking water supply,I'd use a very different collection system, with prefilter, post-filter and possibly chemical treatment. The use of my system is to water the garden.

For those in range of the Lehigh Valley in PA, the water authority has been giving away free plastic barrels for rainwater collection. I just missed out on the last round but they said they'll get another batch to distribute when they have enough people on the waiting list.

http://lcawaterworks.com/home/2011/06/more-rain-barrels-available-reserve-yours-today/

Perhaps your area is different from the Central Valley of California, in which winds bring: lead and other nasties from vehicle engine exhaust, chemicals from agriculture, and smog particles of who-knows-what from the big cities upwind. I would not want to incorporate any more of this stuff into what I eat than I have to.