How To Determine Your Water Main Line Size

Measure Your Supply Pipe Size: Grab a piece of string about 6"(152mm) long and find the location of your water supply pipe (either in your basement, garage, utility area or outside). You’ll know it’s your main supply pipe when you see a shut off valve that shuts off all the water to your home. Strip away any insulation so you can get at the pipe and wrap the string around it. Measure how many inches of string it takes to go around the pipe once. This is the circumference of the pipe (yikes, bad memories of high school geometry!). Using the circumference we can calculate the diameter of the pipe. But let's forget about doing geometry calculations! Based on the string length use the table below to find your pipe size.

It is as simple as 1, 2, 3.

1. Locate your home main line shut-off valve.

Look for either the red or blue handled valve in your garage, basement, utility room, or other location. If you turn this valve off and it shuts off all the faucets in your house, you have located your home's main shut-off valve.

2. Locate the pipe after that shut-off valve.

3. Measure that pipe and size your EWS or CWL unit accordingly using the chart below..

For Copper Pipe
2.75" (70mm)	= 3/4" Pipe
3.53" (90mm)	= 1" Pipe
4.32" (110mm)	= 1 1/4" Pipe
5.10" (130mm)	= 1 1/2" Pipe
For Steel Pipe or Plastic PVC Pipe
3.25" (83mm)	= 3/4" Pipe
4.00" (102mm)	= 1" Pipe
5.00" (127mm)	= 1 1/4" Pipe
6.00" (152mm)	= 1 1/2" Pipe
For Flexible Polyethylene Pipe
2.96-3.33" (75-85mm)	= 3/4" Pipe
3.74-4.24" (95-108mm)	= 1" Pipe
4.90-5.57" (124-141mm)	= 1 1/4" Pipe
5.70-6.28" (45-160mm)	= 1 1/2" Pipe