Iron In Water
It is no small wonder iron is often a concern with well water as it is the fourth most abundant element in the earth’s crust and the single most abundant heavy metal. It is not hazardous to health at levels most often found in drinking water, however as little as 0.3mg/l can stain laundry and fixtures and build up in plumbing.
The challenge is there is no one size fits all solution for dealing with iron in your water supply as iron manifests in several different forms – often at the same time. Additional variables effecting treatment decisions include overall water chemistry, flow rates, pressure and usage. Let’s discuss the most common types of iron and common treatment methods.
Ferrous or “clear water” iron comes out of the tap fully dissolved in the water and clear, but once exposed to oxygen it oxidizes and becomes the “rust” stains you see in toilets and other fixtures. The secret to removing this type of iron is to get it to oxidize completely so it can be filtered effectively before it reaches the house; otherwise it slips through conventional filtration. A water softener will generally remove up to 3 mg/L of iron, but iron must be clear water iron or it will damage the softener resin. Care must be taken if a softener is used to remove iron because it tends to foul the softener resin. A resin cleaning compound must be used regularly to protect the resin. The most common resin cleaning compounds contain sodium hydrosulfite or phosphoric acid. Some water softener salt contains a resin cleaner, however we do not recommend these products as they are more expensive and tend to “bridge” (harden into a solid mass that is difficult to remove from the tank without damaging equipment.) Higher iron concentrations require a different approach. Air injection introduces oxygen between the pump and pressure tank, oxidizing the iron in preparation for filtration. Extremely high iron levels may require additional equipment such as retention tanks and mixing devices. Please note that air injection does require certain parameters be met including adequate pressure and flow – and exceptionally low water temperatures and pH can be problematic. Likewise, if there is Anaerobic Bacteria present, introducing oxygen can create a breeding ground for it. (See below for more information on Anaerobic Bacteria.) Chlorination can also be used to oxidize ferrous iron, but a mechanical approach is generally preferable.
Ferric iron is commonly referred to as “red water” iron because of its rusty appearance. In reality it is simply clear water iron which has been oxidized, usually from dissolved oxygen present in the water supply. This type of iron is not dissolved in the water but instead
suspended in solution. These iron particles are not easily removed with conventional filtration either as filters clog quickly slowing down flow rates and must be changed frequently. Ferrous iron is almost always present as well and will slip right through. The go-to treatment for ferric iron is a custom built backwashable iron filter with our custom media blend. This requires adequate pressure, pH above 7 and regular regeneration.
Iron Bacteria (Anaerobic Bacteria)
Iron bacteria are a type of bacteria that feed on iron in water. As previously mentioned, iron is very common in the ground so is often present in well water. It is important to note that iron bacteria, while a nuisance, is not a health threat although it can make water unpleasant to drink. Iron bacteria manifests in slimy strands and films and musty odour. If your toilet tank is lined with slimy goo, you probably have iron bacteria. It can also colonize in the well casing and piping eventually reducing water flow. You will never get rid of it entirely, however regular shocking of the well will usually keep iron bacteria in check and is recommended at least spring and fall depending on the severity of the problem. Be aware, if there is significant buildup it may take two or three treatments before you have acceptable results. If shocking proves ineffective, anaerobic bacteria treatment systems are available.
Organic Iron & Tannins
Tannins are organic acids that are a by-product of nature’s processes and are produced as water passes through peaty soil and/or decaying vegetation. Organic iron occurs when iron combines with organic acid usually producing yellow or brown water, although it sometimes remains colourless. Organic iron is most frequently the product of shallow wells, river or lake supplied water or wells under the influence of groundwater. Organic iron and tannins cause staining of fixtures, china and fabrics as well as musty or earthy odour and unpleasant taste. Organic iron and tannins can be treated with a water softener or Manganese/Greensand filtration, but in both instances organics must be removed with activated carbon and other variables such as water pressure must be taken into consideration.
Colloidal iron does not occur as often as the other types, but is worth mentioning as it can come about as a side-effect of the treatment process itself. If using chlorine to oxidize iron, the appropriate dosage is essential as over-dosing with chlorine can cause the oxidized particles to fracture and become so small that they slip past the filter. This can also happen if water is run through an iron filter too quickly. If you are treating for iron and still notice staining it does not necessarily mean your system is not working. It may just need some fine tuning. Colloidal iron can also occur in chlorine-treated water supplied municipally by aging distribution systems.
Fracturing can happen with old cast iron or galvanized fittings and introduce colloidal iron into the water supply.
As you can see, iron can be a tricky problem and properly identifying the type of iron with which you are dealing is critical to applying the appropriate method of treatment. Finding a water treatment professional with experience in diagnosing “problem water” and applying suitable equipment is your first step in finding a solution to your concerns.
Groundwater is typically clean and safe for human consumption. The overlying soil acts as a filter eliminating disease-causing microorganisms. Nevertheless, contamination can occur following a break in the well casing, with a contaminated aquifer or because of contaminated surface water entering the well in the case of dug or bored wells.
Well water should be tested for bacteria at minimum annually, however we recommend seasonal checks especially if you keep or live near livestock or have had an adverse result in the past. Rain and snow melt can carry contaminates through the soil to your water source and since bacteria testing is offered *free through your local Ontario health unit, the extra layer of protection is certainly worth the trouble. Simply pick up a package from your local health unit and carefully follow the instructions. Please note you cannot just collect water in any container and drop it off. You must use the specially treated bottles provided. In addition, the sample should be immediately transported in a cooler or refrigerated and transported to the health unit within 24 hours.
About the Test
Microbiological activity in your water is measured by checking for the presence of total coliforms and Escherichia coli. Total coliforms occur naturally in the soil and the human gut so their presence may or may not indicate faecal contamination of the water. Drinking water should contain no more than 10 total coliforms per 100 ml of water. If your sample comes back higher than 10 a repeat sample is in order. Should the repeat sample still come back over 10, the cause should be isolated and corrective action taken as indicated.
If unacceptable levels of either total coliforms or E. coli are found in your water, find another source of water or boil for at least a minute before drinking. Shock treating the well is your first step. Full instructions can be found on the Health Canada website or you can call a professional water treatment company to do this for you. After 48 hours, resample the water. Two consecutive safe tests over one to three weeks are a good result, but you should follow up with resampling in 3 months. If shocking does not correct the problem, the source of the ongoing contamination should be found and corrected, or preventative treatment considered.
Water Treatment Options
There are several ways to treat contaminated water, but the most common are Ultraviolet light and chlorination. Both require microfiltration to improve inactivation of microorganisms and remove particulates, including parasites. If your water has high levels of hardness (calcium/magnesium) or iron additional pre-filtration may be necessary as well. Chemical free UV is the simplest to manage and most often recommended. Annual bulb and pre-filter changes as recommended will provide your family with safe, potable water for years to come.
*Quebec does not offer this service; you will need to use an accredited lab. See link below.
Ministry of Sustainable Development, Environment, and Action against Climate Change
Public Health Ontario
Our UV Suppliers:
Greenway Water Technologies
Why Soft Water?
Water, the “universal solvent,” absorbs iron, odours, minerals and decaying matter… just to mention a few. Our municipal suppliers deliver bacteria-free water via chlorination, but many raw impurities remain. The choice is yours. You live with these impurities and the cost and aggravation that go along with them… or enjoy the benefits and savings of soft water. After all, water is something you and your family use every day.
WHAT ARE THE BENEFITS OF SOFT WATER?
You can see how a water conditioner in your home will not raise your monthly budget… but actually, lower it! It’s a home appliance that pays for itself.
It’s not what you put in your water that counts… it’s what you take out.
Ask us about a mixed bed conditioner to remove municipally introduced chlorine as you soften!
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