There is very little in the code books regarding grey-water systems. I
have engineered a grey water system.
I had another engineer help me with some of the math (math is where
I'm a little weak)
I went in with my numbers, thinking that the water savings were going
to be 25% on water usage savings.
My engineer friend did the math and calculated residential savings at
40-50% and he calculated commercial savings between 75-90% savings on
Does anybody here have any experience with grey-water? So far I have
found very little. There are certain restrictions that apply (piping
has to be marked with purple/yellow for non-potable...instead of just
yellow); I have to use an air gap for my incoming grey-water; I can
charge my system using a jet-pump and a pressure tank instead of using
an elevated gravity-fed design...
Grey-water is a new thing in my area. We do have one city in the
entire state that has seriously taken a look at greywater and actually
makes greywater availble to their customers through a city main and
charges them 75% less for grey water than they are charging for
completely treated water. It's a pretty cool system they have adopted.
I spoke with the guy in charge of that program and there are very few
areas nationwide that make much use of grey-water.
But consider this....I have one customer that is currently spending
over $2000/month for treated water. If this fellow installs a
grey-water system, his water bill (based on actual usage calculations)
will drop from $2000/month down to less than $200/month.
I believe I can give the same results on larger jobs. I'm wondering
why these very large facilities do not install grey-water systems. Is
it because there is virtually nothing on the market addressing the
need or are people scared off by the high cost (it ain't cheap - but
it more than pays for itself through water savings)?
I can't imagine some of these large commercial/industrial/municipal
jobs passing on the opportunity to save big money on their overhead
operating costs. My system will give the largest savings where toilets
and irrigation account for the largest portion of their water bills.
So places like stadiums, schools, dormitories, etc. where there are
lots of toilets that make up a large part of that bill...those places
are perfect. If all you have are toilets, my system will save almost
100% on the water usage bills.