reverse osmosis: frequently
asked
questions

  • Provides 99.99% Purified Drinking Water
  • pH Scale of 06 – 07 on Average
  • Alkaline Water Options Available
  • Saves Money on Bottled Water or Water Pitcher Filters
  • Reduces Plastic Waste – No More Single Use Bottles!
  • Service: Filter Change is Required Annually*

I Have a Water Softener, Doesn’t That Treat My Drinking Water?

No. A water softener removes calcium and magnesium from the water and is usually installed at the point-of-entry (P.O.E.) of the water to the house. A water softener is good for the home’s plumbing and water-related appliances, but does little to improve the taste or quality of your drinking water.

Note: This includes salt-free Water Conditioner systems, such as our Watchman system.


I have a carbon filter under my sink, doesn’t that clean my water?

No. Carbon filters alone only remove a limited number of contaminants, some odors, and some tastes. They do not provide purified water.

Note: This includes refrigerator water filters. They are a simple carbon filter to help improve the taste of the water, not a purifier.


how often should I change my reverse osmosis (r.o.) filters?

All R.O. manufacturers recommend filter replacement at least once per year. An annual filter change replaces the sediment and carbon filters in your system, and sanitizes its components to remove any bacterial buildup inside. After 1 year the carbon filters can have bacteria growing within the filter media. Your local water conditions may necessitate more frequent filter changes. (See Below.)

R.O. membranes have an average lifespan of 2-4 years, depending on your home’s water conditions. The membrane’s life is extended by the presence of a water softener system or other whole-home water treatment. Calcium and magnesium (limescale) are two of the hardest minerals for the R.O. membrane to remove. Sodium added to the water by a softener is much easier on the membrane, and 98% of the sodium will be removed by the membrane during filtration.


* Is It ever Necessary to Change the Filters in the R.O. System Every Six Months?

If you have no water softener or other whole-home water treatment system in place, it is strongly recommended to replace your filters once every 6 months.
If there is no water softener or other system before the R.O., your membrane will also need to be changed more frequently. It is highly recommended to follow the manufacturers’ guidelines. There are systems designed to operate best to give high quality purified water with normal routine maintenance. By changing the pre-filters on a regular six-month basis, you will eliminate dirt and chemicals in the water that will plug the membrane. After six months of use, the carbon filters can have bacteria growing within the filter media.


i have well water. Can i still install a reverse osmosis system?

Well water quality varies widely. Our systems are rated for municipal water conditions and require a water quality analysis to determine if well water conditions are within their scope of operations. A water quality analysis must be completed before any water treatment system(s) are installed in homes with well water, including whole-home options like water softeners and water conditioners.

Customers with well water will need to change their reverse osmosis filters every 6 months, regardless of the presence of a water softener or water conditioner.


Do I need leak protection on my system?

No, but Desert Mountain Water always recommends leak protection to prevent potential water damage to your home. The new technology is less expensive, and it works without batteries. The Flowlok® system is a great insurance policy against stopping leaks!


Will An R.O. Soften my Water?

Yes, but only the water that comes from the R.O. faucet. R.O. water is softened through the reverse osmosis purification process. Hard, untreated water (above 7 grains of hardness) will, however, shorten the life of the R.O. membrane. The harder the water, the shorter the life.

Example: If your incoming water is 15 grains hard, you may only get 2-3 years of life from your membrane.


What Happens to The Impurities That Were in the Water?

They are washed down the drain as wastewater. Unlike filters, the R.O. membrane is self-cleaning. As the source water flows through the module, it is divided into two streams. One stream is forced through the membrane by osmotic pressure – created due to the water pressure on each side of the semi-permeable membrane. The second stream carries the rejected salts, dissolved pollutants, and contaminates, into the drain as wastewater. Therefore, there is a minimum accumulation of debris on the pressure side of the membrane. Charcoal or carbon filters, however, become less efficient with each glass of water drawn through them.

Isn’t Water Wasted Down the Drain with R.O. Systems?

Yes, there is a certain percentage of water from the system that goes to the drain. This water is carrying away the impurities, particles that are too small to be caught by the filters. Desert Mountain Water’s R.O. Systems have an automatic shut-off valve that shuts off the flow of water to the drain when the holding tank is full. This valve stops the R.O. system from continuously running water down the drain, thus conserving water via the R.O. system running only after use.


What Is the Ratio of Wastewater to Pure Water Produced by a Desert Mountain Water High Efficiency Unit?

Our HE (High Efficiency) ratio is 1:1, based on incoming water temperature and pressure, but our membrane supplier has tested and verified the ratio.

This means that for every 1 gallon of purified water that your system produces, 1 gallon of wastewater goes down the drain.


What Is the Ratio of Wastewater to Pure Water Produced by other R.O. Units?

The typical ratio of a non-H.E. system is 4:1, based on incoming water temperature and pressure.

This means that for every 1 gallon of purified water that your system produces, 4 gallons of wastewater go down the drain.


Can This wasteWater Be Saved and Used?

Yes. The drain water is slightly higher in TDS concentration than the incoming water, but as R.O. does not add anything to the water, it can be used to water your lawn or garden. Wastewater is considered non-potable and should never be given to animals.

Note: Applies to R.O. wastewater only. Water Softener water and wastewater contains salt that will harm or kill plants.

How Will I Know the R.O. Is Removing the Dissolved Solids from the Tap Water?

You will be able to tell by the taste and clarity of the water. For example, ice cubes made with the R.O. water are harder, clearer, and last much longer. If you take two clean glasses of the same size and put ice cubes made with R.O. water in one and the same number of ice cubes made from tap water in the other, you will notice that it takes longer for the R.O. ice cubes to melt. When ice cubes made from tap water are melted in a glass, you will most likely see unsightly sediments on the bottom. With R.O. water, the entire glass will remain clear.

Another way of determining the amount of dissolved solids removed from tap water is using a conductivity meter. This meter measures the conductivity the dissolved solids impart to the water. This is converted on the meter scale into parts per million of Total Dissolved Solids (TDS.)

Desert Mountain Water sells TDS testers that you can test your water to determine if the membrane is working. See full instructions with our TDS calculator.


What Is the Importance of Water Pressure to an R.O. System?

It is the pressure of water that forces the water through the membrane for purification and flushes the rejected solids away. Under proper conditions, R.O. systems do not require any electricity to function. The ideal incoming pressure for operating an R.O. system is 60 PSI.

Lower water pressure will result in reduced production and premature fouling of the membrane. Pressure below 40 PSI is considered insufficient and should be boosted using a pressure booster pump.


Will Iron Hurt an R.O.?

Yes. Iron will plug an R.O. membrane, as the membrane is not able to flush iron out. If the water contains 1 PPM or less, there is no need for concern as the membrane will usually last 3-5 years. Higher trace amounts of iron (up to 2 PPM) can be removed by a water softener.

Note: This refers to clear water iron, not red iron. The difference is that clear water iron leaves no visible signs, whereas red iron leaves a reddish-brown discoloration in toilet bowls, tanks, sinks and tubs. If red iron is present, steps to remove the iron will have to be taken, otherwise the warranty will be void.

What Are the Dimensions of Desert Mountain Water’s r.o. systems?

4-Stage HE Module:
15 ¾” Tall x 14″ Wide x 5 ¼” Deep

5-Stage HE Module:
15 ¾” Tall x 16 ¼” Wide x 5 ¼” Deep

Storage Tank:
11″ Diameter x 16″ Tall (standard 3.2gal size)


Does The R.O. Unit Have to Be Mounted Under the Kitchen Sink? 

No. The R.O. system can be mounted in a cabinet to either side of the kitchen sink. It can even be mounted remotely in a garage, basement, or underneath a mobile or park model home.


How Far Can a Line Be Run from the R.O. Unit?

Approximately 20-25 feet with ¼” POLY tubing. For runs longer than that, use 3/8″ POLY tubing. Tubing that runs from the R.O. system to the ice maker should always be POLY tubing, not copper.


Why Not Use Copper Tubing?

Due to R.O. water being very pure, it is what is known as “hungry water.” R.O. water can leach the minerals out of the copper tubing and may cause a metallic taste in the water and ice cubes, and over time, the copper tubing can develop pinhole leaks.

Click here to see our general FAQ’s page.