How to Install an Undersink Water Filtration System?

Charlie Hardcastle

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An under-sink water filter is similar to a countertop filter in that it connects to a cold water pipe underneath your sink. The water passes through the pressurized filter and then comes out the faucet as clean, pure, and safe drinking water. Some under-sink filters use a special tap. Other models direct the entire cold-water supply to the filter, which can be an easy solution for some homeowners.

Under-sink water filters provide permanent access to clean, filtered water without creating any wastewater except if the system was a reverse osmosis water filter. Also, in the case of a reverse osmosis water filter, there will be a storage tank from which filtered water is directed to your faucet. That said, many under-the-sink filters that people commonly opt for aren’t reverse osmosis filters, though they are worth considering despite being slightly more expensive.

The cost of an under-sink water filter depends on the contaminants and particles you want to filter. You can find modest units for less than a hundred dollars, but most only last for six months to three years. If you’re looking for an expensive under-sink filter, you can spend between $150 and $250 on a multi-stage filtration system.

An under-sink water filter is a worthy investment since access to clean water will make life healthier. Since many people worry about the health risks associated with bottled water, an under-sink filter is a great choice. It filters most of the harmful contaminants present in your home’s water supply.

Buy The Right Filtration System

It really goes without saying that there are many different types of water filtration systems. Some are better for you than others. Generally speaking, you will want to buy a filtration system that meets your home’s needs.

For instance, when buying an under sink water filter, consider how many gallons of water you consume each day. If you don’t have a big kitchen, the under sink water filter system is the best option. It doesn’t take up extra space and will filter the water without any problems. You can choose between two or three GPM filters. Depending on your needs, you can select a filter with a flow rate ranging from 0.8 to two GPM. It is essential to check the PSI of the water supply, as this will affect the flow rate too.

You then want to buy a filter that meets this demand for filtered water and fits within your budget.

The filtration system should have a long life, and the filters need to be easy to replace. It should also come with top-quality cartridges that will last for several months. This will save you money as you will not need to replace the cartridge as often. That said the life of the cartridges also depends on how much water you use and the quality of the water coming through the cold water line.

Buy a system that comes with all parts and instructions necessary for installation. If you have any questions, you can contact a certified plumbing service for help.

How Is An Under Sink Water Filter Installed?

An under sink water filter system is easy to install. The installation process is pretty straightforward and does not require a plumbing license. However, you need to make sure your system can withstand the water pressure in your home. A reverse osmosis water filter will have a lower PSI than an ion exchange filter. So, it is essential to follow the manufacturer’s instructions to avoid problems.

Before you start installing the filter, make sure you have a working faucet and install a cold water supply valve to turn the water on and off to the unit.

It is essential to install the water filter in a way to make sure that you can easily access the filter and replace it. Ensure the system has an on/off switch that makes it easy to turn off the water supply to change the filter cartridges or service the unit.

Now that you have an overview of how to approach the installation let’s get into installing the water filter in the next section.

Installing the Under Sink Water Filter System

In a nutshell, the filter you are about to install has an inlet and an outlet. The inlet is where the water enters the filtration system, passes through all the filtering cartridges, and moves out of the outlet. The outlet can be the sink faucet or a faucet that comes with your filtration system. Regardless, this is from where your filtered water will come out.

You can also install the filtration system in a way that does not disrupt your faucet’s normal flow. What this means is that in addition to the water currently being supplied to the faucet, you can have a separate outlet for filtered water. That way, you can choose to use the water from the regular tap to do the dishes and filtered water for drinking and cooking.

You will need:

The following tools below are required for a standard water filter installation. However, you might need a few other things depending on the filtration system.

  • Philips screwdrivers
  • Plastic tubing cutter or a set of box cutters
  • Adjustable jaw wrench
  • An electric drill along with a 1-1/4” drill bit if there is a mounting hole needed for the faucet.
  • If there is an existing hole for a water sprayer, soap dispenser, etc., this hole can also be used for an additional faucet.
  • A sealing tape like Teflon tape or something similar.

Step 1 – Install the faucet

The first step is to install the faucet. If you install an RO faucet, it must be near the sink, where drinking and cooking water are required. You will need around 2 inches of flat surface area to mount the faucet. However, the thickness of the surface shouldn’t exceed an inch and a quarter.

If the sink you are installing the water filtration system under has a water sprayer, that can be disconnected and removed to make room for a faucet. If it does not, then you will have to install one manually.

If you have quartz, granite, or any other type of countertop which can split or crack, you might want to hire a professional to drill the hole.

Step 2 – Install the plumbing

The next step is to connect the water line to the filtration system. The filter head consists of four filter stages (more or less). Each stage will filter the water that flows into the unit. So, there may be a sediment filter, carbon filters, and a few others.

The cold feedwater line should be connected to the inlet adapter. The output adapter will be connected to the faucet. Make sure to turn off the water before using a pair of cutters or box cutters to slice through the pipe, which goes into the existing tap. You then attach an adapter to the line and hook it up to the input. You can attach a tube from the output of the water filter to the faucet. Once the water line is connected, turn on the shutoff valve slowly as the pressure can damage the filter stages. Press the pressure release button to release the trapped air.

Monitor the connections to and from the pipes for leaks. If you see water dripping from them, then patch these up with Teflon tape. However, if everything has been tightly secured, you may not need to use Teflon tape.

Step 3 – Install the filters

Once the above has been completed, you will want to insert the filter heads or filters as they are called into the system. This takes only a few minutes and requires that you insert and twist them into place. However, make sure to refer to the users’ manual for precise instructions on how to install the filters.

Step 4 – Wiring it up

If you have a reverse osmosis system, it will need to be wired up. Generally, these systems only need enough power to power a small pump that pumps the water through the filter. The pump may be rated at around 12 volts or 24 volts, depending on your system. However, this will require running a wire from your filter to a nearby outlet. If there isn’t a power point nearby, you will want to run an extension from the near one to the water filter and then plug it in. make sure that the power outlet is as far away from the water as possible.

Final Step

Keep the faucet open until there is a steady stream of water. However, the initial water from the RO will be discolored with a very high sodium level. This type of water is standard, and it is simply the excess carbon being flushed out of the system (if the filter has a carbon filter). After there is a steady stream of water is coming from the faucet, close it and check for leaks again.

If it is a reverse osmosis unit, it may take until the tank is full or half full until you can get filtered water from the faucet. All of this mainly depends on how the manufacturer has designed the system. Generally, it can take around 30 minutes before you can start using the water from your under-sink water filter.

It would help if you also made provisions for wastewater disposal. In a reverse osmosis system, there is a constant stream of wastewater flowing from the unit. If you’ve installed the system under your sink, you can extend the pipe into the nearby drain line.

Note: Depending on the size of your home the space underneath your kitchen sink may be limited. In this case, a reverse osmosis system can be installed near the sink or on top of it. If you decide to mount it on top of the sink or near it, a shelf will need to be installed to secure the system. Regardless, it should be easy to access the RO system as and when needed.

Final Word

Now that you know how to install an under sink water filtration system you are also now confident knowing that isn’t particularly challenging, you will need to be comfortable working with tools. It also depends on how complex the network of pipes is under your sink. Some homes have sinks with concealed pipes which means you might have to remove tiles and some concrete to access the lines, in which case it is best to hire a professional. You might also want to hire a professional if you are not comfortable working with plumbing systems.

Many under sink water filtration systems are also sold with free installation. Depending on the brand you choose, they may schedule to send a team of professionals to install the unit for you too. So, make sure you inquire about installation before making a purchase.

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