No matter how carefully you maintain your hot tub water chemistry, the water eventually reaches a point where it needs to be replaced entirely. Dissolved solids build up over time that no chemical treatment can remove — and starting fresh periodically is the best way to maintain comfortable, manageable water.
TL;DR
- Most hot tubs should be drained and refilled every 3 to 4 months
- High bather load or water quality issues may require more frequent changes
- Salt water system users may extend the interval slightly with good TDS management
- Draining in New Brunswick requires attention to freeze risk during the process
- The drain and refill is a good opportunity to clean the shell, jets, and filter
Why Regular Draining Is Necessary
Hot tub water accumulates dissolved solids over time — minerals from the source water, chemicals from sanitizing treatments, and organic compounds from bathers. These dissolved solids are measured as Total Dissolved Solids (TDS).
As TDS rises, water becomes harder to balance, chemicals become less effective, and the water may develop an irritating quality for bathers. No chemical treatment can reverse rising TDS — the only solution is to drain and replace the water.
How Often to Drain and Refill
The standard recommendation for most hot tubs is a complete drain and refill every 3 to 4 months. This timeframe assumes moderate bather load — a couple or family using the spa several times per week.
Spas with higher bather loads accumulate dissolved solids faster and may need draining every 2 to 3 months. Spas used infrequently by a single person may be able to extend the interval slightly, though the 3-month guideline is a reasonable default for most New Brunswick owners.
Salt Water System Considerations
Salt water system users produce chlorine from dissolved salt rather than adding chlorine directly — which means no chlorine compounds accumulate in the water over time. However, salt itself and other dissolved solids still accumulate. Salt water system users should monitor TDS levels and drain when they reach the threshold recommended for their system, which may be slightly longer than the standard interval but is not indefinite.
The Drain and Refill Process
Before draining: add a plumbing flush product and run the jets for 15 to 30 minutes to clean biofilm from the internal plumbing lines. This is done before the water is removed so the flush product can do its work before the pipes are empty.
Drain the spa completely through the drain valve or with a submersible pump. Clean the shell surfaces, headrests, and jets while the spa is empty. Rinse all surfaces thoroughly before refilling.
Refill with clean water, adding a metal sequestrant at startup if your source water has high mineral content. Balance pH and alkalinity before adding sanitizer, then allow the spa to heat before use.
Freeze Risk During Draining in New Brunswick
In New Brunswick, draining your hot tub in winter requires careful timing and attention to freeze risk. A spa that is drained in cold weather must be refilled and the heating system reactivated before temperatures drop enough to freeze residual water in the plumbing.
The safest approach for winter draining: choose a mild day when temperatures are above 0C, drain and clean quickly, and refill within a few hours. Do not drain and leave the spa empty overnight in freezing conditions.
Some owners prefer to schedule their drain and refill for spring and fall to avoid the winter freeze risk entirely.
Cleaning During the Drain
An empty spa is the opportunity to perform cleaning tasks that are impractical with water in the spa: cleaning the waterline ring from the shell with appropriate cleaner, cleaning individual jets, cleaning headrests, and rinsing the filter thoroughly or replacing it if it is due for replacement.
This is also the time to inspect the shell for any cracks, chips, or abnormalities that should be addressed before the spa is refilled and operational again.
First Fill After Draining
After filling, allow the spa to heat to operating temperature before adding sanitizer chemicals. Once at temperature, balance pH first (target 7.2 to 7.8), then total alkalinity (80 to 120 ppm), then add your sanitizer to initial dose. Wait several hours and test again before using the spa.
With salt water systems, add the recommended salt charge after filling, allow it to dissolve, and then activate the salt cell according to your system startup procedure.
Disposal of Spa Water
Drained hot tub water should not be discharged into storm drains or directly onto natural areas. In New Brunswick, municipal wastewater systems are typically the appropriate destination for drained spa water — through a laundry sink drain, clean-out access, or similar connection to the sanitary sewer.
If discharging to a yard or garden is the only option, ensure the water is dechlorinated before disposal. Chlorinated water at concentration will harm soil microbiota and plants.
New Brunswick Perspective
Owners who maintain a regular drain and refill schedule — every three months, on a calendar — consistently report easier water chemistry management and fewer problems between changes. The water simply behaves better when it is fresh, and the chemical investment between changes is more effective. Skipping drain cycles to avoid the effort usually costs more in chemical consumption and frustration than the drain and refill would have.
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