---
title: "What Is Fill water? Pool Glossary | Marina Pool Services"
description: "Fill water is the tap or well water used to top off the pool, and its chemistry affects the pool."
url: https://marinapool.multisites.ai/glossary/fill-water
publisher: Marina Pool Services
phone: +1-817-896-1120
quote: https://marinapool.multisites.ai/contact
---

Water chemistry

# Fill water

Fill water is the tap or well water used to top off the pool, and its chemistry affects the pool.

Every time you top off the pool, you add whatever is in your tap or well water. That can include calcium, metals, and phosphates, and it can shift your [pH](https://marinapool.multisites.ai/glossary/ph).

Test your fill water once so you know what you add. If it is high in calcium, the pool will drift toward [scale](https://marinapool.multisites.ai/glossary/scale) faster. If you use well water, test for metals too. Add water slowly, and retest the pool afterward. A pro can help read the results and plan a refill.

[Marina can helpPool Maintenance Services](https://marinapool.multisites.ai/our-services/pool-maintenance-services)

## Related terms

-   [Hard water](https://marinapool.multisites.ai/glossary/hard-water)
-   [Calcium hardness](https://marinapool.multisites.ai/glossary/calcium-hardness)
-   [Partial drain and refill](https://marinapool.multisites.ai/glossary/partial-drain-and-refill)
-   [Phosphates](https://marinapool.multisites.ai/glossary/phosphates)

## Need a hand with your pool?

Call or text and tell us what your pool needs. Estimates are free for qualifying services, and same-day estimates are possible when the schedule allows.

[Call (817) 896-1120](tel:+1-817-896-1120)[Get a quote](https://marinapool.multisites.ai/contact)

![A pool technician working on an equipment pad](https://marinapool.multisites.ai/_astro/technician-equipment-pad.BW5xZMNY_Zum1K5.webp)