How and When to Drain a Fiberglass Pool
We say “Don’t drain your pool.” Then we say, “At some point, every pool will need to be drained.”
So, fiberglass pools: to drain or not to drain? That is the question.
Yes, I know this Hamlet-style pondering can be confusing. But are we contradicting ourselves?
To keep your pool living its best life, don’t jump on the drain train. Problems can happen if the groundwater around an inground swimming pool is higher than the water in the pool, no matter what type of pool it is.
As a rule, never drain your pool yourself. This is always true.
Instead, ask yourself (and your local pool professional) two questions:
- Does my pool need to be drained—i.e., does the problem absolutely require that?
- How can I go about having my pool safely drained?
When should I drain my fiberglass pool?
Does the pool absolutely need to be drained?
Most people assume that when their pool is green or filled with debris, the easiest thing to do is drain it. That’s usually not the case.
It’s risky to drain ANY type of pool—concrete, vinyl liner, or fiberglass.
The question: when do the benefits of draining a pool outweigh the risks?
For example, if a major catastrophic event (like a flood) left 2 feet of debris in the pool, I’d consider draining it. But only if it can be drained safely.
We want to avoid damage to the pool from hydrostatic pressure, so we need to know how much water is around the outside of the pool, and we have to be able to remove that water.
For this, you need a dewatering system.
In our unique installation methodology as part of The River Pools Way, we install a sump pipe that allows you to take the lid off, look down the hole, see how much water you have, and get rid of it easily.
We also consider the type of material used to backfill around the outside of the pool during installation. Clean, crushed stone is the ideal material (again, a key component of The River Pools Way), because it drains well and the point-on-point friction helps hold the material in place. What we're trying to avoid here is bulges developing in the side walls of the pool.
Basically, we are very confident that we can safely drain a fiberglass pool with a sump pipe and stone backfill.
- A pool with a sump pipe and sand backfill: moderately risky.
- A pool with no sump pipe and sand backfill: a straight-up gamble.
But regardless of sump pipe or backfill type, just don't drain the pool unless it's mandatory.
What's mandatory? A necessary pool repair. It's just that simple.
How should I drain my fiberglass pool?
How can I ensure my pool is drained safely?
Big disclaimer: only authorized fiberglass pool professionals should drain a pool. Never drain a pool without professional assistance.
For most (if not all) pool manufacturers, an authorized dealer must drain the pool, or you may void your warranty.
The basic process:
- Verify that the weather will be dry during the entire process.
- Inspect and remove any groundwater.
- Brace the pool.
- Remove the water, making sure that the floor doesn’t lift.
Check the weather first. You’ll need to drain and refill the pool all in dry weather. (If you get a big storm, it could flood around the outside of the pool. The pool wouldn’t have the water pressure to hold up against it.)
Inspect and remove any groundwater. This is where that sump pipe comes in handy.
Brace the pool across the width of the pool. Typically 3 braces are used 18–24 inches down the side walls of the pool.
Start removing the water.
The side walls of the pool may push in from the pressure, which can cause the floor to lift.
As you remove water, inspect the pool floor to verify that it’s not lifting or feeling spongy.
One trick to keep the floor down: put 6–8 big plastic trash cans in the pool when it’s full. As you lower the water level, the water stays in the trash cans and provides downward pressure.
What other maintenance does my fiberglass pool need?
Fiberglass pools need the least maintenance of all three pool types. And the best news of all: 95% of fiberglass pools won't need to be drained for decades.
So are they the most low-maintenance pool? Yes, but they are not no-maintenance. The work is just less intense and less frequent.
- Clean regularly, with products made specifically for fiberglass pools
- Check water chemistry
- Run the pool filter
- Keep water level above the skimmer
River Pools manufactures and installs fiberglass pools in Virginia and Maryland, and we operate in other areas of the country through our nationwide dealers. We know pools, and we’re here for you!
Check out our complete guide to pool maintenance for advice on any issues you may encounter. We want to help you make the most of your pool!
Editor's note: This blog article was updated on December 17, 2019.