# Home Water HQ (homewaterhq.com)

Water filtration buying guides with verified prices, plain-language certification decoding, letter paperwork grades (A-C) from a published rubric, and yearly filter costs.

## Guides
- [Best Whole-House Water Filters](https://homewaterhq.com/best-whole-house-water-filters/): Tank and cartridge systems graded on what they're actually certified to do.
- [Best Under-Sink RO Systems](https://homewaterhq.com/best-under-sink-reverse-osmosis-systems/): Tankless vs tank, and why '50 GPD' usually isn't.
- [Best Countertop Water Filters](https://homewaterhq.com/best-countertop-water-filters/): RO without the plumbing — and the yearly filter bills compared.
- [Best Pitcher Water Filters](https://homewaterhq.com/best-pitcher-water-filters/): The cheapest pitcher to buy is the priciest to own. The numbers inside.
- [Whole-House vs Under-Sink](https://homewaterhq.com/whole-house-vs-under-sink/): Different tools for different problems. Decide by problem, not product.
- [NSF Certifications Explained](https://homewaterhq.com/nsf-certifications-explained/): What 'certified' actually means — the four tricks on every box.
- [What Filters Really Cost Per Year](https://homewaterhq.com/water-filter-cost-per-year/): Every product in our dataset, ranked by the number nobody prints.
- [Water Filter Sizing Guide](https://homewaterhq.com/water-filter-sizing-guide/): GPM, GPD, and cups per fill — sizing each filter type by demand.

## Tools
- [Water Filter Finder by Contaminant](https://homewaterhq.com/water-filter-finder-by-contaminant/): match the dataset's systems to the contaminants in your water — certified vs manufacturer-claimed reductions, ranked by verified coverage. Per-contaminant certification data verified 2026-11-05.
- [Water System Builder](https://homewaterhq.com/water-system-builder/): assemble a stage-by-stage whole-house system (sediment, iron, softener, main filtration, UV, RO) with flow, connection, and stage-order compatibility checked against manufacturers' published specs; ends in a priced build sheet.

## Data
- Full dataset (JSON): https://homewaterhq.com/data/filters.json
- Lite dataset (JSON): https://homewaterhq.com/data/filters-lite.json
- Terms for agents: https://homewaterhq.com/for-agents/

Prices verified 2026-11-03.