With more than 30 years’ experience in the residential and commercial water treatment space, Mark Nelson is a Class 1 Drinking-Water Operator and a CBWA (Canadian Bottled Water Association) Certified Plant Operator. As founder and president of Nelson Water in Ottawa, Mark focuses on dealing with challenging water treatment system designs for problem water. He also heads the largest water bottling plant in the city of Ottawa with a delivery network throughout the Valley.
Many people are interested in RO filtration systems because they can remove a wide variety of contaminants and produce water that’s almost 99% pure. This is a purely mechanical filter system that forces the water through a semi-permeable membrane with very tiny pores. No chemicals are added, and this is a cost-effective solution. But, there is a drawback, this process takes time and this is why many people opt for a point-of-use (POU) system installed at a single faucet (usually at the kitchen sink). In this article, we will look at the larger variant of RO systems which delivers extremely clean water to every faucet, fixture, and water using appliances in the home.
How Does a RO Filter System Work?
At the heart of this system is the aforementioned semi-permeable membrane with very small pores that prevent virtually all particles from passing through except water molecules. It takes significant force to push the water through the filter, and the water is placed under pressure to facilitate this process. This takes time, and for this reason, the water is stored in a tank for easy access. The contaminants are left behind on the surface of the filter, and they are periodically flushed into the drain to keep the pores clear. There are other filters in a RO system; a prefilter removes sediment that could damage the semi-permeable membrane. This is followed by a granular activated carbon (GAC) filter to remove chlorine which can also damage the membrane filter. The next stage is the actual membrane filter that does most of the contaminant removal work. A final filter stage is a second GAC filter that adds some character and a little polish to the filtered water.
What Does a RO Filtration System Remove?
Around 98% of dissolved organic and inorganic matter is removed from the incoming water supply. But, there are many other contaminants that are removed, including lead, arsenic, sodium, nitrates, boron, chromium, mercury, copper, uranium, and many more. These contaminants present a significant threat to health due to their toxicity, and it’s a good idea to remove them entirely. For this reason, many people install a RO filtration system, but this presents some challenges, and the easiest option is a POU system. When a POU RO filtration system is installed, it’s usually located at the kitchen faucet with a storage tank under the kitchen sink. This gives the homeowner access to extremely clean water to fill water pitchers and make high quality ice. But this cleaner water is also excellent for cooking and washing vegetables to a very high standard of cleanliness to reveal their true flavors.
What is a Whole-House RO Filtration System?
As the name suggests, a whole-house RO filtration system will deliver RO water to every faucet, fixture, and water using appliances in the home. This means that you can shower, wash, brush your teeth and clean your home with virtually pure water. But, the installation of a RO system on this scale is a major undertaking, and it takes significant planning to make it work. The pretreatment requirements need to be more formidable, the gallons of RO water that your home needs each day must be calculated, and you will need space to house the equipment. Let’s take a look at three things that you need to consider in more detail:
1. Pretreatment
If the water quality that you receive is very poor, which would usually be a private well water supply, it’s more than likely that you would need other water treatment systems. A RO system will remove salts, chemicals, toxic metals, dissolved organic and inorganic matter, and more. But, the semi-permeable membrane is vulnerable to damage from sediment, sand, rock, and other particulates. For this reason, it’s important to carry out water testing before you choose and install the RO system. There may be a need for specific pretreatments to protect the RO filtration system from damage. This is especially true if you receive hard water because the dissolved calcium, magnesium, and iron can create scale in the RO filter system, which degrades the water quality and output. For this reason, most people in this situation install a water softener before the RO filter system. If the incoming water has a very high concentration of iron, it may be necessary to install a dedicated iron filter to remove it safely.
2. Sizing the RO System
You need a RO filtration system that can meet your daily water usage needs. As a rule of thumb, imagine that most homes consume 60-75 gallons of water per person per day. Younger children tend to use more water, and a house occupied solely by adults tends to use less. So, if you multiply the number of people in the home by the water usage, it’s easy to get to a ballpark figure for the volume of water that you need. This is important because the RO system cannot create filtered water on-demand. The process takes time, and a storage tank is needed that requires space. To put this into some perspective, a family of four may need a 1,000 gallon per day RO system that’s paired with a 250 gallon storage tank. This system would take around 6 hours to fill the storage tank during peak hours, and it could produce up to 42 gallons of RO water per hour. Pairing the correct RO system and storage tank together is important if you want to get some balance between RO water production and adequate storage to meet all your daily needs.
3. Post Treatment
After the RO water exits the storage tank and before it comes into the home, there may be some post treatment. Many whole-house RO systems have a pH adjuster which is also known as an acid neutralizer. RO water is usually 5-6 pH which is considered to be mildly acidic. This water is corrosive, it can damage the plumbing pipes and fixtures, and the pH must be adjusted to make the water neutral and kinder for your family and home.
If you’re interested in a whole-house RO filtration system for your home, contact your local water treatment specialist today.