Get up to 28% off water filtration systems during this one-day sale at HomeDepot.com. Shipping is free for these items. The promotion includes this 1-Stage Whole House Water Filtration System, which listed at $174.59. It falls to $125.03 during the sale. This 10 GPM Whole House Water Filtration and NaturSoft Salt-Free Softener System drops from $2,309 to $1,847.20 today only. These are the best prices we can find anywhere. Sales tax is charged in most states.