Osmosis is a natural process through which water moves from a low solute concentration to a high solute concentration. Reverse osmosis (RO) inverts that process by using a high-pressure pump and a semipermeable membrane. It separates the water molecules from contaminants and impurities, making an RO system effective both as a water purifier and a water softener. Let’s explore everything you should know about choosing an RO system for your home.
Point of Use vs. Point of Entry
A fundamental choice is whether to install a point-of-entry (POE) RO system or one or more point-of-use (POU) systems. POE systems are more expensive and larger in scale, but they have the advantage of providing clean water throughout an entire home. This is possible because they function between the water main and the home’s plumbing system. POU systems, on the other hand, provide filtered water to a particular tap. Under-sink RO systems for kitchens are common examples. There are also POU systems for coffeemakers, showers, and so on.
The best approach for your home depends on your needs. A POU system is cost-effective if you want clean drinking water and don’t mind the one-tap limitation. However, POUs may not be suitable for large households with high water demands or where hard water is a concern. For instance, a POU system in your kitchen won’t improve your shower experience, nor will it protect your pipes, water heater, and so forth.
Tank vs. Tankless
RO is a slow process compared to traditional water purification. Most RO systems have at least one or multiple tanks, allowing them to clean the water in advance and have it ready for you. Tankless systems provide filtered water on demand, but they are slow. Typically, tankless RO systems are compact point-of-use configurations with a dedicated faucet. They can meet the drinking water and cooking water needs of a small to average household.
Sizing Your RO System
The industry generally measures RO systems in gallons per day (GPD). The usual assumption is that each household member will use 75 GPD. As a rule of thumb, the RO system should deliver triple that rate. This provides leeway for high-usage days and ensures that the system runs only for about eight hours on a normal day rather than around the clock.
Another consideration is the size of your tank or tanks. You’ll want a large enough main tank to meet the household’s needs during peak demand. A secondary main tank may be beneficial. Additionally, you can have point-of-use tanks for kitchen sinks and showers. Planning and sizing a point-of-entry system can be complex, so it’s best to let a professional installer handle it.
Reverse Osmosis System Stages
Another core consideration is the stages of an RO system. While the membrane is the only essential stage, most home RO setups also include prefiltration and polishing stages.
Sediment Prefilter
A sediment prefilter traps the largest particles in your water, such as dirt, clay, silt, and rust. These filters are usually relatively inexpensive and can be swapped out as needed. A prefilter preserves the life of the semipermeable membrane, which is significantly more expensive. It also helps avoid the buildup of larger particles within the RO system components. A prefilter is imperative if you have a good system and is highly recommended for homes with municipal water.
Activated Carbon Filter
Activated carbon is a highly absorbent manufactured material. It is one of the most common materials used in point-of-use and point-of-entry water filtration systems. Activated carbon can absorb and neutralize gases and chemicals. It also provides additional mechanical filtration by trapping particulates between the granules and along its surface. Moreover, it improves the smell and taste of drinking water.
Most reverse osmosis systems will have at least one carbon filter, and it’s not uncommon to have as many as three. In these setups, manufacturers optimize the first filter for organic chemicals, such as chlorine, pesticides, and herbicides. The second filter is denser and removes more suspended particles, while the third filter provides polishing filtration after the RO process, which removes any tastes and odors the water may have acquired during storage.
Reverse Osmosis Membrane
After several filtration stages, your water is clean enough to taste the difference. However, there are many potential impurities in the water that you may not be able to see, smell, or taste. This is where the main RO stage comes in. By forcing the water through the membrane, the system removes over 99% of other substances from the water. All of the reject water, which the industry calls “concentrate” or “brine,” drains into your sewer or septic system.
Remineralization
A downside to RO relative to traditional water purification is that it removes healthy minerals as well. Drinking mostly mineral-free water isn’t good for your health, so most systems have a remineralization stage. Some systems remineralize the entire water supply, while more sophisticated setups have point-of-use remineralization, such as for faucets and coffeemakers. Trace mineral drops are an alternative and are commonly used as a solution for tankless POU setups. While they are cheaper initially, using drops will cost you a lot more money over time.
UV Treatment
Ultraviolet (UV) light is an optional step that many brands now offer with their RO systems. RO systems do remove most pathogens, but some bacteria and viruses may remain. Even in small quantities, those microorganisms could make you sick. UV treatment is typically a final stage that provides you with peace of mind. It accomplishes this by neutralizing any bacteria and viruses that may still be present.
Water Waste
A common question from consumers is whether reverse osmosis systems are wasteful. All water treatment systems waste water to some degree, and RO systems discard more than others due to the reject stream. However, the industry has made great strides in minimizing this waste. Many top systems do not use electricity and have a permeate pump that reduces waste by up to 80%.
Consumers may also want to look for the WaterSense label. WaterSense is a program of the U.S. Environmental Protection Agency (EPA) that sets standards for water-using appliances. The EPA evaluates products through independent lab testing and awards the label to products that meet its standards, providing confidence in your purchase.
NSF Certification
Another organization to be aware of is NSF International, formerly known as the National Sanitation Foundation. The NSF is a U.S.-based international public health and safety organization that independently tests RO systems and other water treatment solutions. If the NSF tests a product and it meets its standards, it will carry the NSF label. This label will detail everything that the RO system can remove from your water.
Reverse Osmosis System Installation in Indianapolis
Hope Plumbing, Heating and Cooling is a locally owned and operated plumbing contractor located in Indianapolis, IN. We are proud to be a Rheem Pro Plumber and install all brands and models of RO systems. Our licensed plumbers complete all RO installations according to building codes and manufacturer specifications. We often have specials available, provide free estimates for system installations, and offer flexible financing options with approved credit. Call us today or contact us online with questions about RO systems or to schedule an in-home consultation.
