Check this out http://www.sjrwmd.com/floridawaterst...ures_by_perfor...

1) That version of the MaP report is from March 2007, and does not
list the Costco one piece toilet in question.

Here's a newer version (January 2008), with the Costco Waterridge EL 1-
piece listed with the horrendous 150 MaP:

"...minimum (250 grams) waste removal performance...recommended by MaP
Testing"
"...minimum (350 grams) waste removal performance...specified by the
U.S. Environmental Protection Agency for their WaterSense Program "

http://www.cwwa.ca/pdf_files/Map%201...%20Report1.pdf

I too, saw that 1-piece toilet at Costco and thought hey this looks
great, and 1/2 the price of the Toto Ultramaxes (MaP 700) I recently
bought for our 9-unit apartment building. Glad I checked online first!
I haven't used the Toto Ultramax but at least one tenant has said they
love it, compared to the Kohler Wellworth ELs (MaP 250) they
replaced.

I also was surprised Costco would carry such a badly rated
product....I would suspect this is a case of sloppy or no research
that slipped through at Costco, rather than a new trend (I hope!)

If you buy a toilet that only flushes 150 grams you'll be sorry. Buy
a ToTo or better.

2) More accurately: "Buy a toilet MaP rated 350 or better." All but 3
of 25 Toto toilets in the 2008 MaP report are above 350...however the
Toto EcoSupreme EL 1-piece is barely passing at 350.