Clean water is an absolute necessity. But rather than constantly buying plastic water bottles and slowly ruining the planet, why not filter the water you already have at home? Water purification can get you the cleanest, best-tasting water possible without the waste or cost of bottles. But how do you know which method is right for your home? Should you get a whole-house system, or just keep a filtration pitcher in the fridge? Hmmm.

Here is a clear four-step process to follow when choosing a water filtration for your home.

1. What’s in your water?

First things first, you need to find out what exactly you need to remove from your water. Check your area’s annual water quality report form your water utility, test the water yourself using an at-home test kit or finding a local lab. Most importantly, you want to know if your water contains lead, but any other information you can gather is helpful.

2. What kind of filter removes it?

Once you figure out what’s in your water, you need to figure out which kind of filter removes it. Here’s a breakdown.

  • Activated Carbon Filters remove heavy metals (copper, mercury, lead), chlorine, pesticides, parasites (giardia), and some VOCs.
  • Reverse Osmosis removes perchlorates (chemicals used in dry cleaning).
  • Distillation removes arsenic.

This comprehensive chart from NSF International, an independent, accredited organization that sets standards for water safety and tests and certifies systems, will help you better distinguish the type of filtration you need.

3. Whole-house or point-of-use?

Next you must decide whether you want a whole-house filter or a point-of-use filter.

Whole-house filters

  • Filters the water before it enters your home
  • Used to remove mineral deposits, unpleasant odors, and tastes
  • You still would need to supplement with another type of filter (point-of-use) to remove other contaminants

Point-of-use filters

  • Filters the water just before you use it.
  • Include faucet and undersink systems, pour-through water pitchers, and water bottles
  • Undersink works most effectively and has the option of a reverse-osmosis filter
  • Undersink are more expensive to install

Bottom line: Need a quick, cheap solution that removes heavy metals? Go with a pitcher. For a more permanent solution, go with an undersink model. If your water smells or tastes terrible, but has no contaminants but mineral deposits, go with the whole-house filter.

4. NSF certification

Once you know the type of filtration system you need and the type of filter that fits your home, you need to focus your efforts on finding a filtration system that is NSF-certified. Whether you’re getting a whole-house system, a simple pitcher, or an undersink model, look for the NSF seal to ensure its been tested to remove the contaminants it says it will.