You drink from your reverse osmosis drinking water system every day, and you love that clean crisp taste of your reverse osmosis water, but is the water that is coming from your reverse osmosis system as good as it is supposed to be?
How Do You Test Reverse Osmosis Water Quality? A reverse osmosis system removes dissolved solids in your water which affect the ability of electricity to travel through it. A Total Dissolved Solids meter measures the resistance of electricity through a sample of water. The amount of resistance estimates the number of dissolved solids in the water.
That’s all well and fine, but how does that tell you if the reverse osmosis water that you are drinking is as pure as it is supposed to be? Just what is good quality reverse osmosis water anyway?
What makes reverse osmosis water good or bad?
The primary function of a reverse osmosis filtration system is to filter out dissolved solids from water in order to make it safe for consumption. The process of reverse osmosis was first developed to remove salt from ocean water to make it drinkable.
The water that comes out of a reverse osmosis drinking water system should have considerably less dissolved solids in it than when it first went into the system.
If it does, that’s a good test result, but if the number of total dissolved solids coming out of the system is not much lower than when it went in, that would be a bad result.
The whole point of getting a reverse osmosis drinking water system is to greatly reduce the number of dissolved solids in your drinking water to make is healthier for you and your family.
If it is not accomplishing this, check out my recommended reverse osmosis systems to find a new system that will work great for you, or you can get a replacement reverse osmosis membrane for your reverse osmosis system.
What do I need to test my reverse osmosis drinking water?
The most common type of test that you would want to perform to check the quality of your reverse osmosis water is a test for total dissolved solids.
This test is very simple to do and will tell you if your reverse osmosis drinking water system is producing the quality water that it should be.
In order to test for dissolved solids in your water, you will need a TDS (Total Dissolved Solids) meter. By measuring the resistance of electric current through a sample of water, a TDS meter will give an approximate number of dissolved solids parts per million in water.
It is a simple meter that will display a number on its screen which is the estimated number of dissolved solids in the water. Some TDS meters are more precise than others or have some extra functions to them but I recommend just using a simple TDS meter.
How do I use a TDS meter?
Using a TDS meter to test your water is very simple.
- Press the power button to turn on the meter.
- Remove the sample cap at the bottom of the meter by simply pulling it off.
- Turn on the water supply that you wish to test, and let it run for at least 10 seconds.
- Fill the sample cap with water, and put the cap back onto the meter.
- Wait until the TDS reading stops going up or down, and settles on a number.
- The number that the meter settles on is the TDS reading for that water sample.
Testing just one sample of water usually will just give you half of the whole story. If you are testing to find out if your reverse osmosis system is performing well, you will need to test the water before it goes through your reverse osmosis system and also after it.
Normally, the water feed to a reverse osmosis drinking water system comes from the clod water being supplied to a sink where the reverse osmosis faucet is to be installed.
This means that we want to test the cold water from the sink faucet, and compare it to the water coming from the reverse osmosis drinking water system.
Although opinions of what percentage of Total Dissolved Solids should be removed will vary, and not all reverse osmosis drinking water systems will perform the same, under most circumstances, the TDS meter reading of the water coming from the reverse osmosis drinking water system should be about as much as 10%, and as little as 2% of the TDS reading of the water being feed into the reverse osmosis system.
When a reverse osmosis system is filtering out very high levels of TDS, the percentage of TDS may be higher than normal because the reverse osmosis membrane can only filter out up to a certain amount of TDS based on its size and water pressure.
In other words, where a common situation may be the incoming water has a TDS of 100, and the reverse osmosis system is able to produce water with a TDS of 2. If the incoming water has a TDS of 1000, it may only be able to produce water with a TDS of 50.
A reverse osmosis membrane is normally able to filter out a higher percentage of TDS in water containing a lower amount of TDS.
Higher TDS going into the reverse osmosis membrane can mean lesser quality percentage water coming out of the reverse osmosis drinking water system.
Total Dissolved Solids doesn’t just mean salt.
As stated before, a Total Dissolved Solids meter is just what it sounds like, it gives a reading of the estimated TOTAL dissolved solids contained in a sample of water.
Although sodium (salt) is often a primary contributor to this number, there can be many other solids in the water that will affect this reading.
Any soluble material that can be absorbed by water including minerals, or metals can contribute to a waters’ Total Dissolved Solids. As water travels through the earth, it can come into contact with many dissolvable solids which it will carry along with it.
So even though most people buy a reverse osmosis drinking water system to reduce the level of sodium in their water, it is also helping to reduce many other potential dissolved solids in the water.
What is a good test result when testing reverse osmosis water?
Ideally, a reverse osmosis membrane would remove all dissolved solids from water leaving the Total Dissolved Solids count at 0. But in the real world, a reverse osmosis filtering system is not quite that effective.
Under average circumstances, a reverse osmosis membrane will filter out up to 98% of the Total Dissolved Solids contained in water. In most cases, this is more than effective enough to make the water safer and better-tasting to drink.
As a reverse osmosis membrane wears, it becomes less able to filter out dissolved solids, and the amount of the Total Dissolved Solids that it can remove from the water will become less.
When this starts to happen, the percentage of dissolved solids in the water will gradually creep up from 2% to 3%, 4% and so on.
What should I do if the test results are bad?
Depending on the situation, a reverse osmosis membrane that is still able to remove 90% of the original total dissolved solids is generally considered to be fine.
But once the membrane can no longer remove at least 85% of the dissolved solids in the water, it is time to replace the reverse osmosis membrane along with the reverse osmosis filters.
Why is regular testing of your reverse osmosis water important?
Since most people use their reverse osmosis system every day for drinking water, and even for cooking, they are not likely to notice a gradual change in the taste of the water.
A reverse osmosis membrane will usually lose its ability to properly filter out dissolved solids very gradually. And this means that most people will continue to drink their reverse osmosis water long after the membrane is no longer producing quality water.
By testing your reverse osmosis water regularly, you will know when the reverse osmosis membrane is starting to lose its effectiveness, and therefore you will know when to change the membrane and filters before you and your family are drinking poor quality water.
Does testing reverse osmosis water with a TDS meter mean that it is safe to drink?
Although a reverse osmosis system does remove or greatly reduce many contaminants in water, it is not guaranteed to remove all potentially harmful substances from your drinking water.
You should test your water with a comprehensive water testing kit, and have your water tested for harmful contaminants at a local laboratory.
What other reverse osmosis water testing should I do?
It’s good to be concerned about the water coming out of your reverse osmosis drinking water system, but it is good to test what is going into it as well.
If you have hard water, you should test your water to ensure that it is soft before it goes into your reverse osmosis drinking water system.
Hard minerals can be filtered out by a reverse osmosis membrane, but they can quickly clog the membrane or cause tears in the openings in the membrane which will allow them to get larger and therefore not filter out the dissolved solids that it is meant to filter out.
Chemicals like Chlorine in your water will damage your reverse osmosis membrane, and cause it to need replacement much sooner than normal. If your water is supplied by a municipal water supplier, they are likely adding chlorine to the water to make it safe for consumption.
If you have a carbon whole house filter, it should be able to remove the chlorine from your water. If not, be sure to change your carbon pre-filter on your reverse osmosis system regularly to protect the membrane of the system.
You can test for water hardness, chlorine and other water contaminants with a complete water testing kit.
Where can I get a Total Dissolved Solids meter?
I have found this very simple to use TDS meter from isopurewater.com that you can use for regular testing of your reverse osmosis water.
I highly recommend it for the average reverse osmosis system owner, but isopurewater.com has several other TDS meters that you might like as well.
