Point of entry vs point of use
EPA's WaterSense guide uses two simple terms:
- Point of entry (whole house): installed where water enters the building and distributes treated water for all uses, including showers, toilets and laundry.
- Point of use (under sink): treats water at the tap where you use it. EPA says these are best suited for water used for drinking and cooking.
EPA also points out that many uses, like flushing toilets, do not need extra treatment, and suggests not oversizing a system. On the other hand, CDC notes whole-home treatment makes sense when you need to address something at every tap.
Side-by-side comparison
| Factor | Whole-house filter | Under-sink filter |
|---|---|---|
| What it does | Treats all water entering the home | Treats water at one faucet |
| Best for | Chlorine or chloramine smell in showers, sediment, whole-home comfort; can include softening for scale | Drinking, cooking, coffee and ice |
| Common technology | Sediment pre-filter, carbon media, optional ion-exchange stage | Carbon cartridges or a reverse osmosis system with a dedicated faucet |
| Maintenance | Media or cartridge changes on schedule; backwashing or regeneration on some systems | Cartridge changes; RO units also need periodic membrane replacement |
| Space | Room near the main line (garage, utility area or outside wall), often a drain | Kitchen sink cabinet |
| Installation | Plumbing work at the main line | Simpler; good for condos and apartments |
| Ongoing cost factors | Media life, water for backwash, salt if it softens | Cartridges, membrane, and reject water if it is RO |
When whole-house makes sense
- You smell chlorine or chloramine in the shower and want it gone at every tap.
- You see scale on fixtures, glass and appliances (pair filtration with softening).
- You have sediment showing up in aerators and toilet tanks.
- You own the home and have a place near the main line for equipment.
Living Water's whole-home purification for city water uses Puronics systems that Living Water describes as removing chlorine and chloramine. See the city water system.
When under-sink makes sense
- Your main goal is drinking water, and you are buying bottled water now.
- You live in an apartment or condo, rent, or have no room near the main line.
- You want deeper treatment of drinking water, such as reverse osmosis, without treating water you flush.
An under-sink carbon filter mostly improves taste and odor; an under-sink RO system goes further by reducing dissolved solids. For any specific contaminant, the model must be certified for it (NSF/ANSI 53 for filters, NSF/ANSI 58 for RO), so check the listing.
Which should you choose?
- Under-sink if you only care about what you drink, have limited space, or rent.
- Whole-house if your concerns are in the shower, laundry and fixtures too.
- Both if you want filtered water everywhere and the most polished drinking water at the kitchen tap. This is a common pairing.
Jorge's free in-home water test helps you decide based on your water, not a sales script. Call, text or WhatsApp (305) 793-5974.
https://www.epa.gov/system/files/documents/2025-01/ws-products-home-water-treatment-guide_v2_508.pdf
https://www.cdc.gov/drinking-water/prevention/about-choosing-home-water-filters.html
https://info.nsf.org/Certified/DWTU/
Updated 2026-10-17 · Living Waters · Jorge Canela, Water Quality Specialist