How to Drain and Refill a Hot Tub, Step by Step

Even with perfect chemistry, hot tub water wears out. Dissolved solids from chemicals, sweat and lotions build up until the water won't stay clear. Draining and refilling resets everything.

How often should you drain a hot tub?

For most home hot tubs, every three to four months. Drain sooner if you use the tub heavily, the water stays cloudy or foamy no matter what you do, or chemicals stop working the way they used to. Your spa manual may give a specific schedule.

What you'll need

• A plumbing or line flush cleaner (see drain and refill supplies)
• A submersible pump or garden hose for the drain valve
• Filter cleaner and a filter cleaning tool
• A soft cloth and a non-abrasive surface cleaner
• A hose pre-filter for filling
• Your start-up chemicals: test strips, pH and alkalinity products, sanitizer and shock

Our drain and refill accessories bundle pulls several of these together.

Step by step

1. Flush the lines. The day you drain, add a line flush cleaner and run the jets as the label says. It loosens buildup hiding in the plumbing so it drains out with the old water.
2. Turn off the power at the breaker. Never run the heater or pumps without water.
3. Drain the tub with the drain valve or a submersible pump. Check local rules on where you can drain water treated with chemicals.
4. Clean the filter. Rinse it, soak or spray it with filter cleaner, and replace it if it's worn (full filter cleaning steps).
5. Wipe down the shell with a soft cloth and a spa-safe cleaner. Rinse well so no cleaner is left behind.
6. Refill through the filter housing if your manual recommends it, which helps prevent air locks in the pumps. A hose pre-filter helps remove metals and sediment from fill water.
7. Restore power and let the water circulate and start heating.

Start-up chemicals for fresh water

1. Test the water.
2. Adjust total alkalinity to about 80 to 120 ppm (an alkalinity increaser, usually sodium bicarbonate, raises it; see water balance products).
3. Adjust pH to about 7.2 to 7.8 with Spa Up or Spa Down.
4. In hard water areas, a pH stabilizer like pH Balance Plus added at each refill helps prevent pH drift.
5. Add a metal and stain treatment like Metal Gon if your fill water has iron or copper.
6. Add sanitizer to reach your target range, and shock to finish. A start-up treatment such as EZ Spa Start is another option; follow its label.

New to the weekly routine? Our hot tub chemical guide covers it, and chlorine vs bromine can help if you're thinking of switching sanitizers.

Safety first: always follow the directions on the product label and your hot tub maker's manual. Add chemicals to the water one at a time, never mix chemicals together, and store them dry, cool and out of reach of kids and pets. Questions? Send us a message.