Drinking water filtration

Stages have jobs

Sediment media catches particles. Carbon can reduce chlorine, taste/odor and specific chemicals only when claimed. Micro/ultrafiltration can physically reduce organisms by rated pore/performance. RO reduces many dissolved contaminants but wastes water and needs pressure. UV inactivates microbes but removes nothing.

Certification beats marketing

NSF/ANSI 42 covers aesthetic claims; 53 covers specific health-effect claims; 55 covers UV systems; 58 covers RO. The standard number is not a grade. Read the exact certified contaminant claim, flow and replacement capacity.

Whole tank vs point of use

Fill-side filtration protects the tank but slows filling and cannot prevent contamination after the filter. Point-of-use treatment protects drinking water near the tap and lets the shower keep higher flow. Many travelers use coarse fill protection plus stronger drinking-tap treatment.

Maintenance

A neglected filter can restrict flow or support growth. Record installation date, gallons if available, pressure drop and source conditions. Replace by the maker's limit or earlier after dirty water; sanitize housings and protect cartridges from freezing.

Method

Good at

Does not automatically solve

Sediment

Particles/turbidity

Microbes, dissolved chemicals

Carbon

Taste, chlorine; claimed chemicals

All microbes/metals/salts

UF/MF

Claimed particles/organisms

Dissolved chemicals; every virus

RO

Many dissolved contaminants

All microbes without maintenance

UV

Microbial inactivation

Particles, chemicals, storage recontamination

CHAPTER CHECK

• I can explain the purpose and failure mode of each item in this chapter. • I know which manufacturer limit or water-quality claim controls my choice. • I added the valve, access, drain, measurement or maintenance task to my drawing/checklist.