How can I measure how many gallons of water my hot tub / spa holds, I can contact the manufacturer?
A. Not all manufacturers have exact measurements any way, quite often they upgrade the design or layout and don’t take into account the new water level. Here is what you do next time you are about to refill your spa, get as large of a bucket you can find that you know the exact volume of e.g.. 5 gallon bucket or 20 gallon garbage bucket ( the larger it is the more accurate your measurement will be). Now with a timer in hand fill the bucket of water from the same source you would use to fill the spa and note how much time it took. Now fill the spa and time that as well. Note: don’t use any other water sources, like washing machine or toilets, etc… that may affect the pressure of the source your using to fill the tub. Once the water reaches the normal operating level of you tub you can then calculate how much water is in you tub. Formula; convert time of both fills to common units of measure (second or minutes), then divide the time it took to fill the spa with the time it took to fill
