RO and Filter Change Tips

Although your Culligan Drinking water system is designed for a lifetime of trouble-free use, the system does need occasional maintenance and yearly filter changes to keep it working properly. Here, we will cover a few of the more common questions customers have about changing the filters on their drinking water system.  Please refer to your Owners Manual for specific, step-by-step instructions.

Filter Change Frequency

Your drinking water system utilizes different filters to perform specialized tasks in the purification process. These basically can be broken down into three types: Pre-Membrane filters, Post Membrane filters and the Membrane itself.

The Pre-filter(s) remove excess sediment and organic material, such as chlorine, to prepare the water for the reverse osmosis process (see How Reverse Osmosis Works). Some systems use a single integrated filter for this task while other systems use separate sediment and carbon filters. Regardless of the configuration of your system, these Pre-filters should be changed annually to protect the reverse osmosis membrane and allow it to function as designed.

Likewise, the Post-membrane filter(s) give a final polish to the water. Your system may have just one inline post-filter or “bullet” filter to accomplish this task or, on more advanced systems, it may have a specialty filter such as a coconut shell filter that can be used to adjust the flavor of the water.  Again, regardless of the specifics of your system, the post filter(s) should be changed on an annual basis.

Reverse Osmosis Membrane

The other part of the equation is often the most confusing – the Reverse Osmosis Membrane. This semi-permeable membrane is often called an ultra-filter and works at the molecular level to remove everything from lead and arsenic to viruses in the source water. As long as the pre-filters are changed regularly, this membrane will last five to seven years in most household systems. Of course all source water is different and the life of your membrane will vary based on the quality of the source water and the amount of water purified as well as the frequency of pre-filter replacement. 

It is important to never touch the membrane with bare hands or leave it exposed to the air for extended periods of time as this will foul the elements. A Total Dissolved Solids (TDS) test is used to determine the current condition of the membrane and our service technicians do that every time we change the filters for you. If you are changing the filters yourself, just take samples of your water before the drinking water system (at the regular tap) and after the system (using your Culligan faucet) in clean containers. Make sure to label them (before and after) and bring them to our office for testing – there is no charge for this service.

Turning Off the System

When changing filters, it is important to note the proper sequence for turning off the water to prevent excessive spilling. The best way is to start from the source. Locate the supply connection first. In most installations, we connect to the cold water supply for your kitchen sink. There will be a small (usually blue) valve at that connection. Turn that valve 90 degrees so it is perpendicular to the supply line – now the water is shut off to your system, but you are not done yet.

Next, turn on the Culligan faucet at your sink to allow the entire system to drain. Allow it to run until it stops. There may be more than two gallons of water in the system and storage tank so it may take a bit. Now that the majority of water is out of the system, you can turn off the valve on top of the water storage tank. You should do this before you start disconnecting any lines. There will still be some residual water in the system, but it should be minimal and easily contained with a towel or two.

Sanitizing the System

Each time you change filters, it is recommended that you sanitize the system. Some forums online suggest a mild bleach solution for this. However, the chlorine in the bleach will shorten the life of your membrane and harm the rubber seals and gaskets that keep your system water tight. Instead, we recommend common peroxide that can be purchased at the drug store. By introducing just a capful in the bottom of the sediment filter housing, it will sanitize the entire system when you perform the rinse stage of the standard filter change. We also recommend cleaning the end of your faucet with a swab soaked in peroxide as part of your routine maintenance.

Rinsing the Replacement Filters

You may read in the owners manual or see online that you are to “rinse” the replacement filters before changing them. This is true, but DO NOT rinse them in tap water. This will contaminate them before you even put them into service. It’s better to put them into their respective housings and then run two or three tanks of water through the system before regular use.

After you replace all the filters and reconnect all the fittings, turn the valve on the storage tank back on and then turn the supply line valve back on (parallel to the supply line) at the cold water connection. You will hear water flowing through the system. Allow the storage tank to fill completely.  Now, drain the system as before by turning on the faucet. When it stops allow the storage tank to fill again – and drain it again. Do this one more time. Now your filters have been “rinsed.” Your drinking water system is ready for use.

Keep in mind, we have special reduced service rates for regular maintenance such as filter changes.  Also, if you rent your home drinking water system from us, annual filter changes are included in your service agreement.  So just request a service visit and we will take care of your drinking water system as only a trained Culligan technician can.