What Is Point of Use vs Point of Entry Water Treatment?

Before you compare brands, decide where the treatment goes: one tap or the whole house. For most drinking water worries, one tap is enough and costs far less.

What’s the difference between point of use and point of entry?

A point-of-use (POU) system treats water at a single tap, the CDC explains, while a point-of-entry (POE) or whole-home system treats most or all of the water entering your home. The Minnesota Department of Health lists pitchers, countertop units, faucet filters, refrigerator filters and under-sink units as POU, and calls it a good option for treating only the water you drink and cook with. POE units go on the water line where it enters the house.

The price gap is large. The EPA’s guide to choosing a treatment system says basic pitchers and tap filters usually cost under $100 and reverse osmosis a few hundred dollars, while POE systems can cost thousands and generally need professional installation.

Do you need whole-house water treatment?

Usually not. The EPA notes that many household uses, like flushing toilets and washing clothes, don’t need extra treatment, and suggests treating only the water used for drinking and cooking. For PFAS, the ATSDR says exposure from showering, bathing or washing dishes would be low compared with drinking the water, which is why our guide to PFAS filters starts at the kitchen tap.

POE earns its cost in a few cases:

• Hard water. Minnesota’s treatment fact sheet lists water softeners only as a point-of-entry option, though you can leave toilets, outdoor taps and a drinking tap unsoftened. See hard water.
• Chemicals you could breathe in or absorb. An under-sink filter won’t protect you from a chemical that evaporates in the shower or passes through skin; a whole-house filter treats it before you’re exposed, Minnesota explains. Not all contaminants do this, so ask your health department about yours.
• Serious, ongoing contamination, which is where the EPA says POE systems are best suited.

Some technologies fit one side better. Reverse osmosis, for one, is more practical at a single tap than for the whole house, Minnesota says.