Link: readyrefresh.com [readyrefresh.com]
Combine the current AMEX offer (check your individual offers, YMMV) for $15 off $30 with their existing site-wide 50% off and free delivery offer. Only need to hit $30 total (including bottle deposit, tax etc) to trigger the AMEX offer, there's no minimum from ReadyRefresh. You can also do a one-time delivery and don't have to sign up for recurring deliveries unless you want to.
Not sure if they deliver nationally, so check your zip before ordering.
Example deals (prices include 50% off, not AMEX offer):
Sparkling Natural Spring Water - Black Cherry
Case of 24 - .5 Liter (16.9 oz.) [readyrefresh.com]
Poland Spring® Brand
100% Natural Spring Water
Case of 24 - 700 ml [readyrefresh.com]
USDA-Certified Organic Iced Tea - Half & Half Lemonade Tea
12 Pack of 12 - 16 oz. [readyrefresh.com]
Iced Tea - Lemon
Case of 12 - .5 Liter (16.9 oz.)