What Happens To The Impurities That Were In The Water?
Great question! This is also one of the many reasons why professional systems are more effective (and safer) than pitchers or faucet filters.
Let’s break down exactly what happens to the impurities that were in your water.
1. In a Whole-Home Filter, Contaminants Get Trapped Inside the Media
Whole-home systems that remove chlorine, chloramines, sediment, or metals work by capturing contaminants inside a filtration media.
Examples include:
Catalytic carbon
Activated carbon
Sediment filters
Iron filtration media
Specialty resin
How it works:
As water flows through the media, the contaminants attach to the surface of the media and become trapped. Clean water moves through, while the impurities stay inside the unit until the media is replaced.
Where impurities go:
They remain in the filtration tank until:
The system backwashes them out, or
The media is replaced during maintenance
Nothing cycles back into your drinking water.
2. In a Water Softener, Hardness Minerals Are Flushed Down the Drain
Water softeners don’t filter impurities, they exchange minerals.
Softening resin removes:
Calcium
Magnesium
Some iron (if conditions allow)
During regeneration, the captured minerals are flushed out of the resin bed and sent safely down the drain.
Where impurities go:
Down the drain line during regeneration, not into your drinking water.
This is why softeners require salt: the salt solution “resets” the resin so it can keep removing minerals.
3. In a Reverse Osmosis System, Impurities Are Separated and Washed Away
R.O. removes contaminants at the molecular level using a membrane with microscopic pores.
The membrane separates water into two streams:
• Permeate (Purified Water)
This is the clean water you drink.
• Concentrate (Reject Water)
This is water carrying the impurities that were removed, including:
PFAS
Fluoride
Nitrates
Dissolved solids
Metals
Minerals
Chemicals and microplastics
Where impurities go:
They are flushed out through the R.O. drain line as part of normal operation.
Nothing sits in a tank. Nothing builds up.
Everything is carried away and disposed of automatically.
This is the key difference between R.O. and pitchers: the contaminants don’t stay in the filter, they leave the home entirely.
4. What Happens Inside Pitcher Filters? (Less Ideal)
Pitcher filters trap contaminants in a small carbon block that quickly saturates.
Where impurities go:
They stay inside the filter until replaced, which is why timely replacement is critical.
Reverse osmosis is safer because the contaminants flow out of the home, not into a stagnant filter.
Why This Matters
Understanding how impurities are removed helps you:
Choose the right system
Maintain your system properly
Know when to replace filters or media
Trust the quality of your drinking water
Clean water isn’t about removing “some” contaminants, it’s about removing them completely and ensuring they don’t re-enter your home.
Why Houston Homeowners Trust Environmental ProTech
For over 30 years, we’ve helped families understand what’s in their water and design systems that remove contaminants efficiently, safely, and reliably.
When you schedule a free water test, we’ll show you:
What’s in your water right now
How each system removes those impurities
Where those contaminants go
How to maintain your system for the best performance
We make clean water simple, safe, and transparent.
Call now to schedule your free water test and get a custom explanation of how contaminants are removed in your home.
PS. We have over 30 years experience in bringing clean water to the Houston Homeowners. Our reviews speak for themselves! If you want clean drinking water from your faucet, contact us at 281-495-4420 to schedule your free water test today.
Sources & Further Reading
EPA – Home Water Treatment Basics
https://www.epa.govCDC – Filtration and Water Treatment Methods
https://www.cdc.govWater Quality Association – Reverse Osmosis Technology
https://www.wqa.orgU.S. Geological Survey – Minerals in Drinking Water
https://www.usgs.gov