How to Drain Water from an In-Ground Pool

Draining a pool sounds easy, but if you don’t know how to drain your pool safely, it’s one of those jobs that can go very wrong, very quickly.

At Millennium Pools & Spas, we’ve spent more than 30 years helping homeowners and property managers across Virginia, Washington, D.C., and Maryland safely drain, inspect, and renovate their pools. Here’s what you should know before you even touch a pump.

Safe and Effective Pool Draining

Draining a pool isn’t as simple as dropping in a pump and letting it run. When done incorrectly, the water pressure beneath the pool can cause the shell to crack or even lift out of the ground. That’s why professionals take extra precautions, checking the hydrostatic plugs, local drainage rules, and the surrounding water table before removing a drop of water. We inspect, calculate, and plan. We’ll remove the water safely without putting your pool or your investment at risk.

When Should You Drain Your Pool?

You don’t need to drain your pool every year, but there are a few clear signs it’s time:

• Water chemistry is out of control – When balancing pH and alkalinity no longer works, it’s time for a clean slate.
• You’re starting renovations or repairs – Structural work, crack repair, or deck updates often require a full drain.
• High TDS (Total Dissolved Solids) – If your water looks dull or your chemicals don’t seem to work anymore, it’s probably time.
• Flooding or contamination – If dirty stormwater or debris finds its way in, draining is often the safest solution.

Things to Know Before You Start Draining

Draining might sound easy, but skipping any of these steps can lead to big (and expensive) problems. Before you plug in a pump or open any valves, you need to:

• Turn off all pool equipment, including your filter, lights, and heater, to protect them.
• Check your hydrostatic plugs. These tiny valves release groundwater pressure and prevent your pool from “floating.”
• Know where your water will go. In many areas across Virginia, Washington D.C., and Maryland, pool water must drain to a sanitary sewer, not your lawn.
• Inspect the pool shell. Look for cracks or weak spots that might worsen when the pool is empty.

Tools You’ll Need for the Job

Here’s your quick checklist:

• A submersible pool pump (not your pool’s filter pump. It’s not built for this)
• A discharge hose long enough to reach your drainage area
• Extension cords rated for outdoor use
• Rubber boots and gloves for safety
• Tools to access and adjust hydrostatic plugs

If your system uses a cartridge filter or sand filter, make sure you know how to bypass or shut it down before starting.

Step-by-Step: How to Drain a Pool Safely

Here’s the right way to get it done:

• Power down all equipment
• Place your submersible pool pump at the deepest point in your pool
• Run your discharge hose to a proper drainage location
• Turn on the pump and monitor it regularly
• Stop draining when just a few inches of water remain
• Use a wet vac or mop for the last bit
• Release your hydrostatic plugs if needed to relieve pressure

It’s important to stick around while the pool drains. Leaving it unattended is one of the biggest mistakes people make.

Mistakes That Can Ruin a Pool

We’ve seen it all. Here’s what not to do:

• Draining during heavy rain – Groundwater pressure spikes, and your pool could lift or crack.
• Using the main filter pump instead of a submersible one – You’ll burn it out in no time.
• Ignoring hydrostatic plugs – That’s asking for structural damage.
• Draining too often – Every 3–5 years is usually plenty for most pools.

If anything on this list makes you nervous, that’s a good reason to call the pros.

After the Water’s Gone: What to Do Next

Once your pool is drained, take advantage of the opportunity. It’s the perfect time for:

• Pool inspection and crack repair
• Tile and coping cleaning
• Deck renovation or resurfacing
• Equipment maintenance or upgrades

FAQs: Draining an In-Ground Pool

How Often Should I Drain My Pool?

Most pools only need draining every 3–5 years, depending on water quality.

How Long Does It Take to Drain?

With a submersible pool pump, it usually takes 8–24 hours, depending on size.

Is It Safe to Drain Completely?

Yes, as long as groundwater and hydrostatic plugs are properly managed.

Can I Drain It Myself?

You can, but having a pro ensures it’s done safely and prevents structural issues.

Why Homeowners Trust Millennium Pools & Spas

We specialize in service, renovation, and repair for both residential and commercial pools. For over three decades, we’ve served Virginia, Washington, D.C., and Maryland with expertise you can rely on.

We’re proud members of the Association of Pool and Spa Professionals, have been Honor Roll Rated on Angie’s List, and offer full-service support, from pool inspection to final cleanup. Plus, your project manager stays with you from start to finish, so you’re never left guessing what comes next.

Let’s Get Your Pool Ready for Its Next Season

If your pool needs to be drained, inspected, or repaired, and you don’t know how to drain a pool safely, don’t take chances. The experts at Millennium Pools & Spas are here to handle it the right way. Contact us today to schedule service in Virginia, Washington, D.C., or Maryland and get your pool back in perfect shape for the upcoming season.