The top offer on this page is the $150 off voucher for the G3P800 800 GPD tankless reverse osmosis system, and it is best when you are buying that specific G3P800 unit. Use the $150 off voucher at checkout to reduce the G3P800 price; this product specific coupon applies on the website and requires entering the promo at checkout. Other product specific coupons on the page apply only to their named models.
If you are buying a G3P800: The $150 off voucher above is the pick. It takes $150 off the G3P800 price, which is larger than the Member's Day fixed savings when that specific model is in your cart.
If you are buying an X12-PRO or K6 or G3P600 or G5P700A: Use the product specific coupon for that model. The X12-PRO coupon takes $210 off the X12-PRO; the K6 coupon takes $200 off that instant hot water dispenser RO unit; the G3P600 coupon takes $100 off that unit; the G5P700A coupon takes $50 off the G5P700A alkaline RO system. Pick the coupon that matches the exact model in your cart because these fixed dollar discounts apply directly to their named products.
If your cart is $800 or more but contains no product specific model above: Use the Member's Day $40 off $800 code. That $40 fixed saving requires a minimum purchase of $800 and is website only, so it is the best threshold option when none of the model coupons can be used.
If your cart is $500 to $799 and no product coupon applies: Use the Member's Day $25 off $500 code. It requires a $500 minimum and is the go to for mid size orders that just miss the $800 threshold.
If your cart is $200 to $499 and no product coupon applies: Use the Member's Day $10 off $200 code. It requires $200 minimum and is website only.
For small purchases, first orders and subscriptions: If you are a first time customer and prefer a small percentage saving, signing up for the newsletter gives 5% off your first order; that can beat a small fixed dollar saving if your order is low. For ongoing needs, Subscribe & Save offers 10% off sale products (prices already reduced on product pages) and 5% off replacement filters on subscription deliveries; those discounts apply automatically to qualifying items and need no promo code.
When choosing between these options, compare the single voucher or subscription discount that applies to your exact items and pick the one that produces the lowest cart total. No listed coupon states that codes combine, so treat each as a single use in your order and take whichever leaves the lower total.
Our records show 458 Waterdropfilter offers listed on our page in the 12 months to October 2026 (418 codes and 40 sales). Percentage codes were rare in that time (4), with the biggest at 20% and the typical at 4%. Our team carried out 422 checkout tests across 418 offers in the 12 months to October 2026, so fixed dollar coupons like these are common and well represented in our checks.
