Article 17: Pond Water – Potable Tap Water, by Jeff Richardson - Play It Koi

Your house tap may seem like a constant – constant pressure, constant purity, and constant hardness.  But you would be mistaken.  You need to be cautious when adding large amounts of water to your pond. Your home’s water will come from a water utility company, a cistern, an on-site well, or community well.

Tap Pressure: As discussed previously, house water pressure is rated as medium pressure (20-100 PSI) - typical inlet water pressure to a home is about 40-45 psi (20-60 low and high ends).  Pressure is created by water tanks placed high above the area they serve and/or with pressurizing pumps.  It is easy to think that to lower pressure, all you have to do is partially close a shutoff valve.  Nope, this will only reduce flow, not pressure.  Pressure remains constant within a closed system.  The only way to reduce pressure is a pressure reducing valve.  People give examples of putting a thumb over an end of a hose and the water travels farther.  This is not pressure, but rather orifice size.  Creating a restriction upstream which limits flow and pressure is what causes the stream to shoot farther.  Pick up a Pressure Test Gauge (<$10) which attaches to a water spigot.  Get one with a red test needle that displays highest PSI.  This is important as the pressure overnight in a town’s water system increases when NO one is using water (max pressure).  How is this pertinent to your pond?  Firstly, some auto-fill valves have a PSI max rating.  Next, as shown in article 13, less pressure means less flow which means more time to fill your pond.  When I installed my new fill line, I took pressure test at the spigot and at the end of my line to ensure that I was not exceeding PSI limits to my auto-fill valve.  I also measured my GPM rates through the hose and through the auto-fill valve.  My 75’ hose was rating at 4GPM while the auto-fill valve was only rating 1GPM.  The difference was so great, that I installed a tee with a secondary fill valve so that I could do major water changes at the higher 4GPM.  I also purchased a high quality water meter.  I can watch and time the exact fill rate of my pond.  Remember, during the course of a day, the water pressure can change with the neighborhood usage.  If you suffer from low pressure, you can buy booster pumps that essentially suck water from the plumbing system in order to boost flow output.  Take measurements multiple times throughout a week to establish an average.

Tap Water Composition: As mentioned previously in Article 11, conditioners are added to potable water to make it safe for pond life.  Your local water supplier usually publishes a report of the composition of their water and even what the typical pH, KH, and GH ratings.  Unfortunately, these tests are usually done at the treatment plant and the water travels through miles of pipes before reaching your home (use a test strip to get an idea of your home tap water conditions).  If you have water delivered, the provider should have a test report.  But the cistern, tank and plumbing may add chemicals to the water.  Other chemicals the utility may add to your tap is chlorine and chloramines (chlorine + ammonia).  Chlorine is harmful to fish, healthy bacteria and other pond life.  If the utility performs a test and find pathogens in the water supply, they flush the system with heavy doses of these treatments – so the level is essentially unknown and ever-changing.  This means you must use de-chlorinators every time you fill your pond.  This will render the chlorine into non-harmful chloride (in 2-5 minutes!).  Some conditioners also contain herbal extracts, aloe vera and other stress inhibitors for fish, other contain chelating compounds which bind to heavy metals that may be present in plumbing systems.  Of course, if you are on well water, you needn’t worry about chlorine, but you may still need to have your water tested carefully and add additives to ensure that the water does not contain naturally occurring toxins, pathogens, metals, or too many minerals or other ground chemicals that would be unhealthy to you and your pond.  As with water pressure, test the composition of your water periodically to get an average baseline.  Perform the test from the spigot that feeds your pond.  Understanding your tap water baseline will let you know what pond conditioners to have on-hand.

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