Clean That Water: Filtration and Purification Guide

Grainger Editorial Staff

Most water isn't just water. It might look like unadulterated H2O when it comes from the tap, but there's probably other stuff hiding in that flow of molecules. In fact, the EPA confirms that you can expect that water from public systems will have small amounts of some contaminants.

Whether you want purified water for health reasons, you need it for a manufacturing process or you just think it tastes better, you can use a water filtration and purification system to get rid of some of the stuff that might be in your tap water.

The type of water filtration system you'll need depends on what you're trying to accomplish. Do you just want to make sure your water doesn't taste bad? Or is there harmful stuff in your water that you want to remove?

Improving the Taste and Smell

Water treatment plants use a long series of steps to remove unwanted material and make water safe to drink. As a final measure, some systems add disinfecting chemicals to kill any pathogens that remain. That's why some tap water has a "chlorine" taste.

Many water filters can reduce chlorine taste and odor. In fact, according to the Centers for Disease Control and Prevention (CDC), improving the taste is the main purpose of popular refrigerator water filters.

Reducing Contaminants and Pathogens

Some water problems are more serious than undesirable taste and smell. There are harmful chemicals and microorganisms that can be present in your water. Lead, arsenic and Cryptosporidium cysts are examples of contaminants that can some water filters and purification systems can remove.

If eliminating a harmful chemical or microorganism is your goal, it's important to look for a water filter that's effective against the specific thing you want to remove, because no single filter can remove everything.

Knowing What's in Your Water

So how do you know what contaminants your water filters should target? To get a better idea of what's in the water from your community's system, you can consult its consumer confidence report (CCR).

The Environmental Protection Agency (EPA) requires that public systems provide these reports on drinking water quality to their customers, and the CDC explains how to interpret them. You'll learn about any EPA-recognized contaminants that have been found in your public system's water.

If you get your water from a private well, the CDC recommends testing its water at least once per year. Private wells are not regulated by the EPA.

Comparing Water Filters Using NSF Certifications

One way to make sure a water purification system can do what you want it to do is to look at its NSF certification. NSF International establishes public health standards and tests products, and several of its standards are related to water treatment and safety. Here's a good rule of thumb:

  • If you only care about the taste, you can look for NSF 42 certification. This indicates a filter that reduces impurities that can make water taste and smell bad.
  • If you're trying to eliminate unhealthy stuff from your water, you can also look for NSF 53 certification. This indicates a filter certified to reduce a contaminant with a health effect. For example, if you want to eliminate lead, you can look for a filter with NSF 53 certification for lead removal.

Understanding RO and UV Systems

Filtration is the most common way to clean water, but there are other water purification technologies to consider.

Reverse osmosis (RO) systems pass water through semipermeable membranes using high pressure. They're effective at removing a wide range of contaminants, and most bottled water is processed using RO systems. But RO systems also produce a significant amount of water waste. NSF 58 indicates a system certified as using reverse osmosis.

Ultraviolet (UV) light systems use high-energy light to kill microorganisms like protozoa, bacteria and viruses. However, UV systems don't remove any chemical contaminants on their own. NSF 55 indicates a system certified as decontaminating water with UV light.

Getting the Water Where You Need it

There are different kinds of water filtration systems for use in different places:

  • In commercial facilities and homes, whole-building systems treat the water after it comes in from the service line. Under-the-sink systems treat only the water that flows through the connected tap.
  • For appliances like ice machines, refrigerators and water bottle filling stations, water filters may be integrated into the unit or installed on the line leading to it.
  • In industrial facilities, process filters treat the water before it's used by processing and manufacturing equipment.

Getting the Most out of Your Water Filtration System

If your water filter isn't properly maintained, it can actually do more harm than good, according to the CDC. Make sure to change the filter regularly and follow the manufacturer's maintenance instructions.

Frequently Asked Questions

Q: What is hard water?

A: Hard water has calcium and magnesium ions dissolved in it. It's not toxic, but it can have undesirable consequences, like making detergents less effective or depositing scale in pipes, boilers and other equipment. 

Water softeners work by exchanging calcium and magnesium ions for sodium and potassium ions. They don't use filtration, so they don't remove other chemicals or microorganisms.

Q: Is purified water the same as distilled water?

A: Distilled water is one type of purified water. The Food and Drug Administration (FDA) regulates how bottled water manufacturers can describe their products, and "purified water" means bottled water that has been processed to meet the U.S. Pharmacopeia definition of purified water. Distillation is one way to produce purified water for bottling—but not all purified water is distilled, so the two are not necessarily interchangeable

The information contained in this article is intended for general information purposes only and is based on information available as of the initial date of publication. No representation is made that the information or references are complete or remain current. This article is not a substitute for review of current applicable government regulations, industry standards, or other standards specific to your business and/or activities and should not be construed as legal advice or opinion. Readers with specific questions should refer to the applicable standards or consult with an attorney.

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