As irrigation contractors deal with drought and water restrictions, many are looking to alternate water sources. The key is to choose one that won’t kill plants but also doesn’t require too much processing, says Art Elmers, Netafim USA district sales manager.
At a seminar at the Irrigation Show in Las Vegas, Elmers explained how to evaluate water sources and find the right one for a site.
Alternate sources of water include rainwater, storm water, graywater, foundation water, air conditioning condensate, process water, reclaimed water, surface water and groundwater. Each has its own contaminants to consider: particulate, organic and chemical.
Particulate. This includes sand, silt and clay that can clog sprinklers and drip irrigation valves, and cause remote control valve failure. Filtration will generally work in these situations but the appropriate type of filtration depends on the sources, contaminants and volume of water, as well as the final use of the water. Manufacturer’s recommendations will tell you what level of protection you need.
“If you’re worried about what the water looks like, you’re not going to get the turbidity out of the water if you’re using a disc filter or a media filter,” Elmers said. “You will with a self-cleaning filter.”
Biological. Biological contaminants can either be organic, like algae, or pathogenic, like bacteria.
To deal with organic contaminants, you can use something like an aerating fountain or dyes to keep light from hitting the bottom of the pond and prevents anything from growing. Or run it over rock to aerate it before it gets into the pond.
“A lot of people try to mitigate the problem from just in the irrigation system but I tell people a lot can be done from treating that water you’re going to pull from before the algae grows,” Elmers said, “Keep your source water clean.”
That will reduce the cost of filtration, which will still be necessary. Media or disk filtration works best.
While it’s impossible to get rid of all pathogens in water, you’ll want to limit them as much as possible using a chlorinator. A good controller is the key to making sure there isn’t too much chlorine.
Another option is UV treatments. “The benefit versus the chlorinator is I don’t have to go out and buy more UV,” Elmers says.
Chemical. The first thing to do when choosing a source is to conduct a water test on all of your options, looking out for salt and iron in particular.
To keep salts out of the water, use an injection system to add gypsum, which will bind to the salt and keep it from getting into the plants or soil. Elmers said it’s one of the most expensive options, so he’d treat a particulate issue before he’d use a source with salt.
If iron is the issue, the biggest problems are staining and iron slime – a bacteria that will grow inside the tubing and clog the emitters. A gas chlorinator will clump the iron together, and it can then be filtered out through a self-cleaning media or disk filter.
You probably need a self-cleaning filter. “This could be one of the most expensive,” Elmers said.
Carbonates. Often referred to as ‘hard water,’ carbonates will even attach themselves to plastics.
You can treat it through amendments to the source water or you can treat the results.
“Most of the time people are looking at on a yearly basis going in and doing a chemical acid treatment and basically it will clear off the plaque or hard water deposits.”
To do that, you’ll need a permanent or temporary injection system to run the acid through. Ultimately, you’re looking at filtration at least, along with some sort of disinfection if necessary.
“Make sure you do the water test and you determine what you have before you start considering what you use as an alternate water source. And dollars can be from a little to a lot,” Elmers said.
For more of our coverage from the IA Show, click here.