Key Takeaways
Bottom Line: Draining and refilling your hot tub every 3-4 months keeps your water fresh, your equipment running smoothly, and your hot tub experience enjoyable. The process takes about 4-6 hours total, but most of that time is hands-off waiting for your tub to fill and heat.
Here's what you need to know: Turn off power, drain using your spa's drain valve or a drainage tool, clean the shell and filters, refill through the primary filter, and rebalance your water chemistry. Don't forget to flush your plumbing lines for the deepest clean.
Let's be honest—draining and refilling your hot tub isn't exactly the most exciting part of spa ownership. But it's one of those essential tasks that keeps your water sparkling clean and your hot tub running like a dream.
Think of it like changing the oil in your car. You might not love doing it, but skipping it leads to bigger problems down the road. Fresh water means better hot tub chemistry, less strain on your filtration system, and way more enjoyable time spent relaxing in your water spa.
Whether you're dealing with stubborn cloudiness, planning seasonal hot tub maintenance, or just hitting that 3-4 month mark, this guide will walk you through everything you need to know.
When to Drain and Refill Your Hot Tub
Most hot tub owners should drain and refill every 3-4 months, but your usage patterns matter more than the calendar. Heavy use means more oils, lotions, and organic matter in your water—all of which build up over time.
Here are the telltale signs it's time for fresh water:
Your water looks dull or cloudy despite proper hot tub cleaning efforts. You're adding more chemicals than usual to maintain balance. There's a persistent musty or chemical smell. Your skin feels sticky or itchy after using the tub. Test strips show readings that won't stabilize no matter what you do.
Pro Tip: The Bather Load Formula
Here's a quick way to estimate when you need fresh water: Divide your spa's water volume (in litres) by the average number of daily bathers, then divide by 12. For example, a 1,500L tub with 2 daily users would be 1,500 ÷ 2 ÷ 12 = roughly 62 days between changes.
Seasonal changes are also perfect opportunities for a complete refresh. Spring cleaning after winter storage, or preparing your hot tub outside for summer entertaining, are natural times to start fresh.
What You'll Need Before You Start
Gathering your supplies first saves time and prevents those frustrating mid-project trips to find what you need. Here's your complete checklist:
Essential Tools: Garden hose, submersible pump or drainage tool, soft cloths or sponges, bucket for filter soaking, and a filter cleaning tool if you have one.
Hot Tub Chemicals for Restart: Fresh sanitizer, shock treatment, pH adjuster, alkalinity increaser, and stain and scale prevention.
Cleaning Supplies: Spa shell cleaner, filter cleaner, and optionally a line flush product for deep plumbing cleaning.
Optional but Helpful: A pre-filter attachment for your hose can remove impurities from your fill water, and a spa vacuum makes cleanup easier.
Pro Tip: Check Your Water Source
If you're on hard water or well water, consider using a pre-filter attachment when refilling. It removes many impurities that can cause staining or make balancing your hot tub chemistry more difficult.
Step 1: Turn Off Power and Prepare Your Hot Tub
Safety first—always turn off power to your hot tub at the main breaker before draining. This prevents pumps from running dry, which can damage expensive parts of hot tub systems.
Remove your hot tub cover and set it aside in a safe place where it won't get damaged. This is also a great time to give it a good cleaning with a cover-specific cleaner.
If you're planning to flush your plumbing lines (which we highly recommend), add your line flush product now while the pumps can still circulate it. Run the pumps for 15-20 minutes, then turn off the power and let it sit for a few hours or overnight.
Take photos of your current chemical readings with test strips. This gives you a baseline to work from when you refill and helps you understand how your water changes over time.
Step 2: Drain Your Hot Tub Completely
Most hot tubs have a built-in drain valve, usually located on the side or bottom of the spa. It might be hidden behind an access panel, so check your owner's manual if you're not sure where to find it.
Attach a garden hose to the drain valve and run it to an appropriate drainage area. Make sure you're following local regulations about where spa water can be discharged—many areas require it to go into sanitary sewers rather than storm drains.
Open the drain valve and be patient. Gravity drainage can take 2-4 hours depending on your tub size and the elevation difference to your drainage point.
Pro Tip: Speed Things Up
Want to drain faster? A submersible pump or quick-drain tool can empty your tub in 30-45 minutes instead of hours. Plus, some tools let you vacuum debris while draining—killing two birds with one stone.
While your tub drains, remove and inspect your hot tub filter. This is the perfect time for deep hot tub cleaning of your filtration system. Rinse filters thoroughly and soak them in filter cleaner according to package directions.
Don't forget about secondary filters or debris bags if your spa has them. Clean or replace these components while you have easy access.
Step 3: Clean the Empty Shell and Jets
With your tub empty, you can see everything that's been hiding under the water. Don't be shocked if you find some buildup around the waterline or in the corners—that's totally normal.
Use a spa-safe cleaner to wipe down all surfaces. Avoid household cleaners that can leave residues and cause foaming later. A specialized spa cleaner works best for removing oils, scale, and waterline buildup.
Pay special attention to the jets—they can harbour bacteria and biofilm if not cleaned regularly. A soft brush or cloth can help get into the crevices where buildup likes to hide.
Check for any cracks, loose fittings, or other issues while you have full access. It's much easier to spot and address problems when the shell is empty and visible.
If you notice white flakes or slimy residue, you might be dealing with biofilm buildup. This is exactly why regular draining and hot tub maintenance matter so much for long-term enjoyment.
Step 4: Inspect and Clean All Components
While your hot tub filter soaks, take advantage of having everything accessible. Remove and clean any removable headrests, cup holders, or other accessories.
Inspect your drain valve and any visible plumbing connections. Look for signs of wear, corrosion, or mineral buildup that might need attention.
This is also a great time to check your hot tub's skimmer basket (if it has one) and clean out any debris that's accumulated there.
Pro Tip: Document Everything
Take photos of any issues you notice. This helps track problems over time and provides useful info if you need to call for service. Plus, it's easier to remember what normal looks like when you have reference photos.
If you're replacing your filter in hot tub during this maintenance cycle, now's the time to install the new one. Fresh filters provide better water clarity and reduce strain on your hot tub's circulation system.
Step 5: Refill Your Hot Tub Properly
Here's where many people make a mistake that can cause problems later. Always fill through your primary filter—that's the filter with the grate or cage covering the suction fitting.
Place your hose directly into the filter housing and start filling. This prevents airlocks in your plumbing system and ensures water reaches all the internal components properly.
Fill to the middle of your skimmer opening or to the level indicated in your owner's manual. Overfilling can cause issues with skimmer operation, while underfilling can lead to pump problems.
Be patient during the fill process—it typically takes 45-90 minutes depending on your tub size and water pressure. Use this time to organize your hot tub chemicals and plan your startup sequence.
Pro Tip: Temperature Matters
Don't add chemicals until your water reaches at least 85°F (29°C). Chemical reactions work more predictably in warmer water, and you'll get more accurate test readings once everything is properly dissolved.
Step 6: Restart and Balance Water Chemistry
Once your tub is filled, restore power and prime your pumps according to your spa's instructions. Most systems will do this automatically, but some require manual priming to get water flowing properly.
Now comes the critical part—balancing your hot tub chemistry from scratch. Start with alkalinity, then pH, then sanitizer. This order matters because alkalinity acts as a buffer for pH, making the whole system more stable.
Follow this sequence for best results:
1. Test and Adjust Alkalinity (100-120 ppm): Use alkalinity increaser if needed. This creates a stable foundation for pH control.
2. Test and Adjust pH (7.2-7.6): Use pH decreaser or pH increaser as needed. Proper pH ensures sanitizers work effectively and water feels comfortable.
3. Shock the Water: Add non-chlorine shock to oxidize any remaining contaminants and establish a clean baseline.
4. Add Sanitizer: Whether you use chlorine or bromine, establish your target sanitizer level (3ppm for chlorine, 4-6ppm for bromine).
5. Add Water Conditioners: Products like water conditioner and stain prevention help maintain water quality and protect your equipment.
Pro Tip: Take Your Time
Add chemicals gradually and allow 20-30 minutes of circulation between additions. This prevents overdosing and gives you more accurate test readings. Remember—you can always add more, but you can't take chemicals out.
Step 7: Final System Check and Optimization
With your basic water chemistry balanced, run through a complete system check. Test all jets, pumps, lights, and any other features to make sure everything is working properly after the drain and refill process.
Let your hot tub run for several hours, then retest and fine-tune your chemistry. It's normal to need minor adjustments as everything settles in.
Consider adding beneficial accessories like a Zorbie to reduce oils and foaming, or a mineral sanitizer to reduce chemical usage and improve water feel.
Once your sanitizer levels are within safe ranges (typically 1-3ppm chlorine or 3-5ppm bromine), your spa is ready to enjoy. Fresh water with properly balanced chemistry makes such a difference in how your hot tub feels and performs.
Maintenance Tips to Extend Time Between Drain and Fills
Good ongoing hot tub maintenance can extend the life of your water and reduce how often you need to go through this process. Here are the key strategies:
Shower Before Soaking: Removing lotions, oils, and soap residue before entering dramatically reduces contamination load on your water.
Regular Filter Cleaning: Clean your hot tub filter weekly with a quick rinse and monthly with a deep clean. Clean filters catch more contaminants and maintain better water flow.
Consistent Chemical Maintenance: Test your water 2-3 times per week and maintain proper sanitizer levels. Prevention is easier than correction.
Use Quality Products: Cheap chemicals often contain fillers and impurities that can actually make water problems worse. Stick with proven brands designed specifically for hot tubs.
Pro Tip: Keep a Maintenance Log
Track your chemical additions, test results, and any issues in a simple log. This helps you spot patterns and catch problems before they become serious. Many spa owners find that consistency in maintenance dramatically improves their overall experience.
Frequently Asked Questions
How long does it take to drain and refill a hot tub?
The complete process typically takes 4-6 hours total, but most of that is passive time waiting for drainage and heating. Active work time is usually 1-2 hours spread throughout the day.
Can I use my regular garden hose to refill my hot tub?
Yes, but consider using a pre-filter attachment if you have hard water or well water. This removes impurities that can cause staining or make chemical balancing more difficult.
How often should I replace my hot tub filter during drain and refill?
Spa filters should be replaced every 6-12 months depending on usage. If your filter looks worn, has permanent discoloration, or doesn't come clean despite proper cleaning, it's time for a new one.
What's the best time of year to drain and refill my hot tub?
Spring and fall are ideal because temperatures are moderate. Avoid extremely hot or cold days—chemical reactions work best at moderate temperatures, and you'll be more comfortable working outside.
Why does my hot tub water look cloudy right after refilling?
Cloudy water immediately after refilling usually indicates either air bubbles (which will dissipate) or impurities in your source water. If cloudiness persists after 24 hours of circulation and proper chemical treatment, you may need additional filtration or water treatment.
Should I clean my hot tub plumbing lines every time I drain and refill?
Line flushing isn't necessary every drain and fill, but it's recommended every 3-4 drain cycles or if you're experiencing recurring water quality issues. It removes biofilm and buildup from internal plumbing that regular cleaning can't reach.
Related Articles
Want to learn more about keeping your hot tub in perfect condition? Check out these helpful guides:
