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Thread: whats in your water?

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    whats in your water?

    Just wanted to share an article I got in my water bill a couple of months ago. In order to understand your pool completely you must understand what happens to the water before you fill it up. I am curious what the gurus here think about this. Obviously this would be different based on where you live even the street you live on. It was taken from Gwinnett County Water Words.

    The Water Treatment Process
    Because of the excellent water quality of water from Lake Lanier, Gwinnett is able to utilize what is known as a direct filtration process for purification. Incoming water is first disinfected with ozone, an extremely powerful oxidant that kills bacteria, inactivates viruses and protozoans, and oxidizes naturally occuring organic compounds found in surface waters. Following ozonation, two chemicals known as coagulants are added to facilitate removal of suspended matter from the water. These chemicals are ferric chlroide and a liquid cationic polymer. Immediately after addition of these chemicals a short (one minute), intense mixing process takes place, followed by a slower more gentle mix period of 15 minutes. This process is called flocculation. After flocculation, water moves to the filtration step. Filters consist of fourt feet of anthracite, sitting on top of one foot of sand. The filter media (the sand and anthracite) is made up of very specific sized grains to achieve maximum removal of suspended material. After filtration, water receives its final chemical application on its way to on-site storage, until it is pumped into the water distribution system.

    Gwinnett uses chlorine as the final disinfectant. State and federal safe drinking act regulations require that a disinfectant residual be maintaind throughout the water distribution system. Typical chlorine residuals are 1.8-2.0 mg/l leaving the water treatment plant. Residuals gradually decrease through the distribution system. Georgia law requires fluoridation of drinking water to prevent dental caries in children. Naturally occuring fluoride in waters in this part of the state are .3-.4 mg/l. Enough fluoride is added at the water treatment plant to bring the fluoride level to .8 mg/l a concentration recommended by the american dental association. Water from lake lanier is very "soft", meaning that it has low levels of dissolved minerals. Soft water is also very corrosive, and steps are taken to reduce this corrosivity, using a phosphate-based corrosion inhibitor. The corrosion inhibitor (an ortho/polyphosphate blend) minimizes corrosion of metal pipes and plumbing fixtures. Corrosion inhibitors are most effective in a ph range of 7.2-7.5 units. Water from lake lanier is usually slightly acidic with a ph of about 6.8. Finished water ph is adjusted to 7.2 units (just slightly basic) with a liquid lime ( calcium hydroxide) product.

    They alos list contaminants as follows
    Copper .126 ppm source is corrosion of household plumbing systems and natural deposits
    lead <1.3 ppb source is corrosion of household plumbing systems and natural deposits
    fluoride .79 ppm source erosion of natural deposits and water additive
    nitrate/nitrite .28 ppm sourse run off from fertilizer use, septic tanks, sewage
    bromodichloromethane 1.6 ppb source by product of drinking water chlorination
    chloroform 2.7 ppb soure by product of drinking water chlorination
    chlorodibromomethane .54 ppb by product of chlorination
    total trihalomethanes 25.1 ppb by product of chlorination
    total haloacetic acids 17.7 ppb by product of chlorination
    bromate <.005 ppm by product of chlorination
    total coliform bacteria .8 naturally present in the environment


    Just so you know out of the tap my water is typically tested as follows
    FC 0.5
    CC 1.0
    alk 30
    ch 50
    cya 0

  2. Back To Top    #2

    Join Date
    Jun 2007
    Location
    Atlanta, GA
    Posts
    71
    I get:
    PH 7.4
    FC .5
    TC 1 though it is probably a bit less than this
    ALK 20
    CH 30

    Sandy Springs, Nesbit Ferry. We're in that stupid little arm that Fulton County forgot about. We're closer to DeKalb and Gwinnet facilities than Fulton. But the water's really good.

    I wonder why our ALK and CH is less than yours. I also think these levels change a lot, though they stay in this low range.
    Location: Atlanta, Georgia.
    Pool: 15,000 gallon 32'x18', 3'-6' deep in-ground gunite pool, Sta-Rite 3 125 GPM 2-filter cartrige, 1.5 HP Sta-Rite pump, solar heater, Goldline SWG, Jandy controls, opaque automatic CoverStar solar pool cover, 3 waterfalls (not from spa).
    Spa: 485 gallon in-ground square acrylic over fiberglass suspended over gunite Sunset brand spa, isolated system, natural gas heater, 2-speed (4hp/11hp) main pump, 3hp booster pump, chlorine sanitized.

    To my pool store owner, nothing is more important than my pool and my money.

    Richard's PoolEquations Spreadsheet

  3. Back To Top    #3

    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,085
    My tap water is as follows and closely matches what is reported in the annual water quality report:

    FC 0
    CC 1
    pH 7.7
    TA 80
    CH 55 (color hue mostly changed on drop 5; intensity changed a little on drop 6)
    CYA 0

    The Combined Chlorine (CC) is due to my water system using monochloramine as the residual disinfectant instead of chlorine. Many water systems are switching over to avoid disinfection by-products (DPBs) from chlorine and to ensure that the residual lasts longer. One nice side effect of this is that it lets me test whether our under-the-sink water filter is working properly since it produces 0 CC (and 0 FC) when it is in good shape.

    The water report only reports Total Hardness, not Calcium Hardness, but I was able to roughly calculate that based on typical calcium to magnesium ratios in our area's water.

    Well water is typically far higher in TA, CH or both. The water from our water system is a mix of 75% runoff reservoir with 25% river water (and some groundwater wells).

    All other contaminants are at miniscule levels. The only items of significance (other than the above) are copper at 0.1 ppm, chloride at around 20 ppm, sulfate at 9 ppm, TDS at 130 ppm, zinc at 0.4 ppm, and sodium at 18 ppm.

    Richard
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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