Sulfates
The maximum level of sulfate suggested by the World Health Organization (WHO) in the Guidelines for Drinking-water Quality, set up in Geneva, 1993, is 500 mg/l. EU standards are more recent, 1998, complete and strict than the WHO standards, suggesting a maximum of 250 mg/l of sulfate in water intended for human consumption.
Some soils and rocks contain sulfate minerals. As groundwater moves through these, some of the sulfate is dissolved into the water.
Some minerals that contain sulfate are sodium sulfate (Glauber's salt), magnesium sulfate (Epsom salt), and calcium sulfate (gypsum).
Magnesium sulfate Sodium sulfate Calcium sulfate
(Epsom's salt) (Glauber's salt) (gypsum)
Health risks for humans who drink water containing high sulfate levelsPeople not used to drinking water with high levels of sulfate can experience dehydration and diarrhea. Kids are often more sensitive to sulfate than adults. As a safety measure, water with a sulfate level exceeding 400 mg/l should not be used in the preparation of baby food. Older children and adults become used to high sulfate levels after a few days |
Is sulfate dangerous for animals?Animals are also sensitive to high levels of sulfate. In young animals, high levels may cause severe, chronic diarrhea, and in some cases, death. As with humans, animals tend to become used to sulfate over time. Diluting water high in sulfate with water low in sulfate can help avoid problems of diarrhea and dehydration in young animals and animals not used to drinking high sulfate water. The proportion of water high in sulfate to water low in sulfate can be progressively increased until the animals can admit the high sulfate water. Contact your local veterinary for more information. |
| Other problems caused by sulfateSulfate gives a bitter or medicinal taste to water if it exceeds a concentration of 250 mg/l. This may make it unpleasant to drink the water. |
There are three types of treatment systems that will remove sulfate from your drinking water: reverse osmosis, distillation, or ion exchange. Carbon filters, water softeners and sediment filters will not remove sulfate. Water softeners exclusively change magnesium or calcium sulfate into sodium sulfate, which is more laxative.
Reverse osmosis (RO) is a water treatment system that eliminates most dissolved elements and chemicals, such as sulfate, from water by pushing the water through a plastic surface similar to cellophane known as a "semipermeable membrane." Generally, it can eliminate between 93 and 99 % of the sulfate in drinking water. This depends on the type of unit. Click here for more information on reverse osmosis treatments. |
| Distillation is a water treatment system in which water is boiled, and then the steam is cooled until it condenses into a separate container. The dissolved substances, such as sulfate, remain in the boiling pot. Click here for more information on the process of distillation. |
Ion Exchange is the most known method of eliminating big quantities of sulfate from water for public, livestock, and commercial supplies, but is not generally used for individual household water treatment. It is a process where one element or chemical is replaced for another. |
If both a water softener and a sulfate elimination system are used, the water softener is generally placed before the sulfate elimination system.
Any water treatment system needs adequate operation and maintenance to ensure that it functions properly over time. It is important to follow the recommendations of the manufacturer for the maintenance of the water treatment system.