How to Install an Under-Sink Water Filtration System

Installing an under-sink water filtration system is one of the most effective ways to ensure you have clean, great-tasting water right from your kitchen tap. While it may seem challenging, many filtration systems are designed with DIY installation in mind, making it a straightforward project for most homeowners. In this guide, we'll walk you through each step of the installation process so you can enjoy the benefits of filtered water without the hassle of complicated setups or hiring a professional.

Can you install an under-sink water filtration system by yourself?

Yes, many under-sink water filtration systems are designed for DIY installation so that you can tackle this project yourself with basic tools and step-by-step instructions. Typically, installation involves attaching the filtration system to the cold water line and mounting it under the sink. Some systems also require the addition of a dedicated faucet for dispensing the filtered water, which may mean drilling a small hole in the sink or countertop. For countertop materials like granite or quartz, drilling can be more challenging and may require specialized tools or professional assistance.

Basic filtration systems usually involve fewer steps and can be installed in a couple of hours; while advanced reverse osmosis (RO) systems are more complex, particularly handy individuals should be able to install these without issue as well.

Benefits of an under-sink water filtration system

An under-sink water filtration system offers a range of benefits that can enhance water quality, convenience, and even cost savings for homeowners. Here are some key advantages.

Improved water quality: Under-sink filters can effectively remove common water contaminants like chlorine, lead, pesticides, sediments, and bacteria, providing cleaner and safer drinking water. This can lead to better-tasting and better-smelling water as well.

Cost savings: Investing in a home filtration system can reduce or eliminate the need to buy bottled water, leading to long-term savings. Additionally, the cost of replacing filters periodically is often lower than purchasing bottled water continuously.

Convenience and ease of use: Unlike countertop or pitcher filters, under-sink systems provide filtered water directly from the tap, making it convenient for cooking, drinking, and other daily uses. There’s no need to wait for water to filter or to refill a pitcher.

Discreet and space-saving: Since the system is installed under the sink, it doesn’t take up counter space or interfere with kitchen aesthetics. The only visible part is usually a dedicated faucet for the filtered water, keeping your kitchen looking clean and uncluttered.

High filtration capacity: Under-sink systems typically have larger filter capacities than pitchers or faucet-mounted filters, allowing them to process a significant amount of water before needing a filter replacement. This makes them a good option for larger households or frequent water use.

Environmental benefits: By reducing the need for bottled water, under-sink filtration systems can help decrease plastic waste.

Customizable filtration options: There are various types of filters for specific needs, such as reverse osmosis for removing dissolved solids or carbon filters for improving taste and odor. Choose a system based on their water quality concerns.

Better for cooking and appliances: Filtered water can improve the taste of coffee, tea, and recipes prepared with water. It can also be gentler on appliances like kettles and coffee makers, reducing mineral buildup and extending their lifespan.

How to install an under-sink water filtration system

Installing an under-sink water filtration system is a reasonably straightforward process and can be accomplished easily with the right tools and know-how. Though the steps might vary slightly based on the brand of under-sink water filter you buy, the process should be similar to the steps outlined below.

Tools and materials needed

Adjustable wrench
Phillips and flathead screwdrivers
Power drill
Teflon tape
Bucket or towel (to catch any water spills)
Filtration system kit with all necessary parts and instructions

1. Choose the installation location

Choose mounting location: Decide where you want to place the filter housing on the inside wall of the cabinet, making sure there’s enough space for the filter cartridges to be removed and replaced.
Mark and drill pilot holes: Using the mounting bracket as a guide, mark the holes where the filter will attach, then drill pilot holes.

2. Turn off the water supply

Turn off the water supply: Locate the cold water shutoff valve under the sink and turn it off by rotating it clockwise.
Release pressure: Open the cold water faucet at the sink to release any residual pressure in the line.

3. Route cold water line

Disconnect the cold water line: Place a bucket under the cold water valve to catch any spills, then disconnect the cold water supply line from the shutoff valve using an adjustable wrench.
Attach the adapter valve: Wrap Teflon tape around the threads of the shutoff valve, then screw on the adapter valve from the filtration kit.
Reconnect the cold water line: Attach the cold water line to the adapter valve, ensuring all connections are tight.

4. Mount the filter housing

Measure and cut tubing: Measure the tubing that will run between the water supply adapter and the filter’s inlet valve. Cut the tubing to the required length using a sharp knife or tubing cutter.
Attach tubing to inlet valve: Insert one end into the filter inlet valve, ensuring a snug fit. Secure with any clips or fasteners provided in the kit.
Connect the tubing to the filtered faucet (if applicable): If your system has a separate faucet, attach a second length of tubing from the filter’s outlet to the filtered faucet’s inlet.

5. Install the filter faucet (optional)

Drill a hole for the faucet (if necessary): If your sink doesn’t have a pre-drilled hole for the filtered water faucet, drill a 1/4" or 1/2" hole in a suitable location on the sink or countertop. Be cautious if you’re drilling through granite or quartz; you may need a diamond drill bit or professional assistance.
Mount the faucet: Insert the faucet stem through the hole and secure it in place from below with the mounting hardware.
Connect the tubing: Attach the filtered water line tubing to the faucet stem and ensure it’s secure.

6. Check Connections and Test

Double-check connections: Ensure all fittings and tubing connections are tight and secure.
Turn on the cold water supply: Slowly turn the cold water supply valve back on and check for any leaks around the fittings.
Flush the system: Open the filtered faucet (if applicable) and let the water run for 5–10 minutes to flush out any air and loose carbon particles from the filter. This step is essential to prepare the filter for use and clear out any contaminants from the installation process.

Step 8: Monitor for Leaks

Inspect for leaks: Check all connections for any signs of leaking. Tighten any connections as needed.
Dispose of wastewater properly: After flushing the system, dispose of the water used during the initial flush.

Post-installation considerations

After installing an under-sink water filtration system, there are a few things you should consider and monitor to ensure the system’s effectiveness.

Regular filter replacement

The filters in under-sink systems need periodic replacement, typically every 6 to 12 months, depending on the system and water usage. Worn-out filters can reduce the system’s effectiveness and even allow contaminants to pass through into your water. Make a reminder on your phone or calendar to replace your filter periodically so you don’t forget!

Monitor water pressure

Some filtration systems require a specific range of water pressure to work efficiently. High pressure can damage filters, while low water pressure might mean the filters are clogged and need replacement. Keep an eye on your water pressure and make adjustments accordingly.

Periodic cleaning

Over time, residue can build up inside the system, particularly if the water has high mineral content. If this is the case, you can give the system components a good cleaning and remove any lingering residue. But in most cases, replacing the filter takes care of the cleaning process.

Inspect for leaks

Since the system is under the sink, leaks can sometimes go unnoticed until they cause water damage. Peek under the sink regularly to make sure no leaks are happening, especially around the joints and fittings. You can also invest in a leak detection system to make this step a bit easier.

We recommend the Acetal Leak Detector - 1/4" OD Connection for that extra bit of added security. This versatile leak detector works with a wide variety of filtration systems and includes a reliable automatic shutoff procedure.

Quality testing

Testing the filtered water quality occasionally ensures the system is working effectively. Water test kits can check for contaminants the filter is supposed to remove, such as lead, chlorine, and other chemicals.

Learn how to test your water at home with a water test kit →

Pay attention to changes in taste or smell

If the water starts tasting or smelling different, it may be a sign that the filter is due for a replacement or that there’s an issue with the filtration system that needs checking. If you regularly clean and inspect the system and change the filter, changes in water taste or smell might be a sign of a bigger issue.

5 best under-sink water filtration systems

Need some guidance on which under-sink water filtration system to buy? Here are our top picks of the most effective water filtration systems that can suit almost any budget or need.

1. Pentair FreshPoint F2000-B2M 2-Stage Under Counter Filtration System VOCs Monitored

The Pentair Freshpoint F2000-B2M is one of the best under-sink water filtration systems, certified to reduce up to 98% of PFOA/PFOS. This system is straightforward to install and delivers delicious filtered water wherever you need it most.

2. Pentair FreshPoint F3000-B2M 3-Stage Under Counter Filtration System VOCs Monitored

If you get water from a well with exceptionally high sediment levels, Pentair's 3-stage version of the FreshPoint filtration system is the best choice. This system is designed to handle a higher level of sediment and other contaminants so your drinking water stays clean.

3. Everpure H-300 Drinking Water Filter System – DIY Kit

If you’re looking for a more cost-effective option, consider the DIY kit for Everpure’s H-300 filtration system. The Everpure H-300 filter features advanced prefiltration technology with a pleated filter membrane, offering an extended surface area and longer lifespan. It effectively reduces chlorine taste and odor, lead, cloudiness, mold, and algae while preserving essential minerals.

4. Everpure EF-3000 Full Flow Drinking Water Filter System

If you’ve got limited space, the Everpure EF-3000 is the perfect under-sink water filtration system. This filter is just as powerful as the H-300 but has a smaller footprint, making it ideal for small apartments, half-baths, and other areas where under-sink space is limited.

5. Neo-Pure 10" Carbon Block Undersink Drinking Water System

You can still enjoy fresh, filtered water on a budget with the Neo-Pure 10” Carbon Block filtration system. Tiny but mighty, this under-sink filtration system fits under almost any sink and can be customized to provide four different levels of filtration.

Fresh, filtered water made easy

Setting up an under-sink water filtration system can be rewarding, providing easy access to clean water while enhancing your home’s sustainability. With time and the right tools, you can complete the installation and enjoy fresh, filtered water at your fingertips.

Remember to follow up with regular filter changes to keep your system running smoothly. If you’re ever uncertain, don’t hesitate to seek professional help, especially when dealing with more complex setups.

When it comes to all things water, Fresh Water Systems has your back. Whether you have questions about a filtration system install or are looking for the best filter options for your home, we can help! Reach out to our amazing team or browse through our collection of water filtration systems today.