Hot Tub Soup What’s really in your Spa water

Why professional pool and spa service technicians recommend draining and refilling your spa with fresh water at least every three months.

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Homeowners that are new to being spa owners are always shocked and surprised when I tell them they should drain and refill their spa on a one to three-month basis depending on how high the use and bather load is. After all it’s basically a big bathtub, no one wants to bath in someone else's bathwater.  Commercial spas with high bather loads sometimes need to be drained daily.

Homeowners always ask, is that really necessary? do we have to? the short answer is in order to maintain clean healthy safe water, YES. Along with scheduled filter cleanings, the proper water balance should test as follows (we recommend the Taylor Technologies test kit k-1003 for homeowners)

pH 7.4-7.6, Bromine 4-6ppm, Total Alkalinity 80-120 ppm, Calcium Hardness 150-200 ppm,

An average bather in a hot tub / spa will bring with them over 100 million bacteria into the water while bathing, joining the already present organisms living in the water from previous bathing, organisms such as bio-film, (bacteria are harbored in bio-film which protects them from disinfectants) parasites, virus, algae, mold, mildew, spores. Compound that with human wastes such as urine, sweat, mucous, tears, saliva, and other bodily fluids. Can you see where this is going? Yuck. But wait we are not done with our recipe. We forgot the man-made products, some examples of these are soaps, oils, lotions, make up, hair products deodorants, anti-perspirants, and perfumes.

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A survey conducted by EPA and Environmental Working Groups showed that the average adult uses nine personal care products each day consisting of 125 unique ingredients. Most all of these personal care products are shed into your spa water upon immersion. An average swimmer in a pool sweats about one pint per hour into the pool water, but an average spa bather sweats about 3x that or three pints of sweat per hour in the 100-104 degree spa water. To further gross you out there are 185 different substances in human urine and sweat.  Of those 185 substances, 115 of them are nitrogenous substances.  14 are lipids and or organic acids. 22 are vitamins, and 35 are hormones.

Some of the largest organic components of sweat and urine are creatinine. Creatinine is a waste product that comes from the normal wear and tear on muscles of the body. Everyone has creatinine in their bloodstream.  When this creatinine combines with chlorine or bromine they produce N-chloro or N-bromo compounds referred to as chloramines and bromamines.  These bromamines and chloramines require HUGE amounts of oxidization to destroy and get rid of them.

I could go into a lot more detail that will just confuse you with chemical reactions between oxidizers and organic materials that produce trihalomethanes such as chloroform  dibromochloromethane and bromoform and the byproducts of these such as cyanogen, halide, halopicrines, haloacetic acids and haloketones, but let’s get out of bio lab and back on track. Regardless of what we professionals call them, chlorine and bromine in spa water eventually become chlorides and bromides and raise the TDS (total dissolved solids) level of the water.  There are over 20 tests that can be performed on your pool and spa water, however many are not always necessary in normal situations. Pool and spa water need to test 7 (Total chlorine/bromine, free chlorine / bromine, Total Alkalinity, pH, Calcium Hardness, TDS, Cyanuric Acid) of the 7 tests, three are very slow to change and need testing less often ( CYA, TDS, Calcium hardness)  and the others ( pH , free chlorine, alkalinity) change rapidly and need to be monitored more frequently in some cases hourly in commercial spas. For residential homeowners I recommend weekly testing.

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I can hear you thinking to yourself Oh My goodness I need to drain and clean my spa now and fill with fresh water. Most likely yes you should.

This is one factor that definitely prevents most pool and spa professionals from EVER wanting to enter into a hotel or resort commercial spa. We know what’s in that water.