This is a common question that we get a lot. It seems that a number of people have irrigation systems that use well water to water their grass, shrubs or gardens. They do this even if they are connected to the city water supply for their homes, because of the large amount of water that is used for irrigating and the costs associated with paying for the city water.
However, the well water often contains significant amounts of iron, and when sprinkler heads spray out the water, the iron which is left behind when the water evaporates, leaves tremendous stains. It may stain the grass, bushes, plants and all the vegetation. That’s certainly bad enough, but what is worse to some people is the stains that are left on the home, sidewalks, vehicles and the like.
So, what do you do? Well, the first thing you have to determine is what exactly is in the water. Yes, there is iron, but what other contaminants are there that could “compete” with that iron or react with it. You need to know the pH and other characteristics of that water. You can’t properly treat water unless you know EXACTLY what is in it, so a good water analysis is imperative. Next, you need to determine how many gallons of water are used on a the heaviest water usage day. They you have to figure out what the peak flow rate in gallons per minute (GPM) would be. This would mean taking into consideration who many heads are on at one time, how many GPM each head uses and how many zones there are. Only when we are armed with this information, can we determine what the best course of action will be.
To remove iron properly, it must be oxidized and filtered out. This can only be accomplished with the use of a filter that uses some type of manganese dioxide or catalytic media which reacts with the iron. Depending upon the water characteristics, an oxidizer may be required, such as oxygen, chlorine, hydrogen peroxide or ozone.
There are chemicals such as Rid-O-Rust that coat surfaces to help prevent stains, but don’t forget that the iron is still in the water and when the water dries the iron will be left behind. Uses of chemicals like Rid-O-Rust is expensive and delivers less than desirable results. The best results are always obtained when you oxidize the iron and completely remove it!
Remember, that irrigation systems often use hundreds or thousands of gallons a day. You can’t expect to take a home system and have it work under those conditions. Quite frequently, it is best to use a backwashing filter or filters that use Filox, Pyrolox, Adox, Catalox, Birm or Greensand Plus with a low-level chlorine feel ahead of the media. There should be no chlorine in the irrigation water and this type of system can work for years with minimal maintenance.
In my opinion, where thousands of gallons are needed a day, the Greensand Plus system works the best, with a Chlorine feed ahead of this to keep the Greensand Plus in a completely regenerated state. Catalytic carbon with a hydrogen peroxide feed just ahead of the catalytic carbon tanks is absolutely the best method to acheive 100% eradication, but the cost of hydrogen peroxide can be prohibitive compared to the low cost of chlorine.
Also, a system utilizing air injection may be used but in order for it to be effective, you will need to have multiple tanks so as to not use more than 500-600 gallons of treated water in each tank.