Water System Leak Gauge
Please visit my Home Page
If you're not into making stuff that sprays water, it's possible to buy, rent, or borrow a portable water meter for a few bucks. Ask your local water utility, hardware rent-all, or building dept.
This gauge was built to verify whether my water pipes were leaking and running the well dry. It won't pinpoint a leak, but it will show the actual volume of loss.
~as free as it gets~
why it's useful
how it works
drawing, parts list & prices
the hippy version
how to use it the math
Why it's useful
The standard leak check is to simply pressurize the system and watch for pressure dropping on a gauge dial like the one shown on the right. This is required for contractors because everything should be new, so any drop at all means poor work. . . Howevah:
If your system was installed by unknown yahoos 30 years ago, and today's test indicates a leak, you might wonder if it's worth digging up the property for $1000+ to replace a badly glued fitting when you don't know the leaks volume. A standard test won't tell that because of the thing that makes pressure tanks work: that large systems can drop more slowly than small systems with the same size leak because pipes and hoses expand under pressure and they sometimes contain air bubbles. Water doesn't compress much but bubbles do. With those two factors, the same size leak will loose pressure more slowly in a large system than in a small system causing the leak to appear to be smaller. The gizmo described below maintains normal pressure in the system so there are no variations in volume.
Parts list and Drawing
These are new parts prices (rounded off) that I looked up as of April 2014, but it can be made from garage sale scraps for a lot less.
The Hippy Version : has the same general loop shaped like "LA" with 2 valves, but is made from drip irrigation parts and costs 80% less, even cheaper ( but not nearly as easy to use) as the above portable water meter.
click to enlarge
- $30 - plastic and copper pipe & fittings
- $14 - kitchen timer or stopwatch from amazon, incl. shipping, needs to count up from zero
- $8 - various water hose connectors & adaptors
- $15 - air compressor regulator from ebay incl. shipping
- Here's Ebay for cheap air pressure regulators, but some listed there are just needle valves with a gauge attached (not actually a regulator). Get one something like this picture at right, with a diaphragm valve & gauge rated above the water pressure of your system. Should cost at least $8 or $10.
- $15 - pressure air hose & fittings, ditto ebay
It doesn't use a pressure regulator, dial gauges, bicycle pump air fitting, copper tube fittings, or brass hose barbs w/ stainless clamps. It relies instead on a high loop (the top of the "A") to contain enough air when pressurized to form a bubble without adding one (w/ the bicycle pump). The ruler is moved to locate on the edge of the bubble and sticks to the tube w/ tape. Instead of a pressure regulator, an obsolete style propane bottle (or something, maybe a hose from a neighbors house) could be used to pressurize the system. An upside down propane bottle is filled from empty with water from the same system, the air thus compressed like a well pressure tank will match the house pressure. Works the same way as the one in the drawing and in the procedure below (next).
USE: (refer to the layout drawing above).
- measure the house water pressure with a test gauge
- connect the hose fitting (part "O") to a faucet in the water line to be tested, but don't turn it on yet
- set the pressure regulator on your air compressor or reserve tank to the house pressure
- close the blue and open the red valve on the gizmo so there's equal pressure on both sides of the bubble
- If the water pressure is high the bubble will be tiny so add some air through part "Q" with a bicycle pump
- turn on the faucet connected to the hose.
- open the blue valve, so that tank air pressure equals the house pressure
- close the red valve
- carry the timer/stopwatch with you to wherever the main shut off valve to the house is located, simultaneously close that valve and start the timer
- take a nap or drink some tea for a few hours. Don't flush or turn on any water in the system.
- wake up, write down the timer reading and measure the bubble's position, do the math.
To find out how much a toilet valve leaks:
- turn off the main valve to the house
- turn off the valve to the toilet (next to the floor)
- do a system check
- re-pressurize the system by opening and closing the main valve
- turn the toilet valve back on
- do another check
- subtract any difference in the results.
The Math The distance that the water level (at the bottom of the bubble) moves during the timed interval equals the rate of the leak. A pressurized 1/2 inch vinyl tube (0.506 inch inside dia. used in the gauge) holds about 0.2 cubic inch (or 0.11 fl oz) of water per linear inch of tube. If the bubble moves
1 inch in 5 minutes = 1.32 fl.oz. in an hour, = 0.24 gallons a day, = 7.2 (US) gallons per month.
1 inch in 1 minute = 37.2 (US) gallons per month
5 inches in 1 minute = 186 (US) gallons per month (GPMo).
The GPMo formula is:
GPMo = a / (t / (i * z)) / b
a = 43220 = (60 minutes x 24 hrs x 30 days)
i = inches measured
z = 0.11 = (inches3 x .20098 = fl oz per inch) cu in to fl oz conversion)
t = time elapsed in minutes
b = 128 = fl oz per gallon (US), or 153.7 (Imperial)
____ How many sheep are in farmer Brown's field?
A side effect of this gauge is that if it's left attached after the house pressure falls below some point (maybe you were asleep), the air bubble will continue on into the house water lines. Air in the lines isn't a big deal w/ water pipes, because the air will come out the first time the faucet is turned on after the main valve is reopened. But someone might use this gizmo to test gas lines which could explode if oxygen is introduced into a pressurized gas environment, so be aware of the danger. If you feel fire proof, lucky, or merely know what you're doing, you might replace the compressed air with propane, (or whatever the gas is) from a pressure regulated bottle, but don't mention my name at the ER. Keep water out of the gas pipe (don't fall asleep).
Congratulations for reading this clear through, here's some kitties.
Honestly, this is probably the best price for a simpler device
P3 P0550 Water Meter $10.75 Amazon.com