DiscountFilterStore.com runs the 15% off code for Tier1 replacement filters as its main offer this month. This code is the best choice if you're buying Tier1 filters online, though other discounts may save you more depending on what category of filters you need and how much you're spending.
The 15% off code for Tier1 filters applies to all Tier1 replacement filters in home, garden, health, and beauty. If you're shopping for air filters instead, you'll want the separate 15% off air filters code, which covers all air filters including replacements for home air purifiers and household air filters. Both codes expire on October 19, 2026.
On smaller orders or specific product categories, look at the fixed price deals. Pool and spa filters start at $9, undersink water filtration systems are priced under $56, and air conditioner replacement filters begin at $35. These fixed prices may undercut the percentage discounts if the item you want is at the lower end of those ranges, or if you're buying just one filter. The 5% off code for the 2404 Pro Products Water Test Kit applies only to that specific item.
On a cart mixing filter types from different categories, the 40% off sale for buying filters from another category can outperform the percentage codes. This sale cannot be combined with other promotions, so if you're eligible for it, you'll need to choose between it and one of the percentage codes. The sale applies automatically at checkout.
If you're buying the USWF Tankless RO Water Filter System, that item has a dedicated 39% off sale, which typically beats a 15% code. On selected products from the broader catalog, you can save up to 25% depending on which items are marked down.
On any order, you can apply the free shipping code to eliminate shipping costs. Whether this saves you money depends on what the shipping fee would otherwise be and whether it stacks with other codes; the terms don't say. Compare the final total with free shipping against the final total with one of the percentage codes applied, and choose whichever is lower for your basket.
Our team tested 124 DiscountFilterStore.com codes at checkout in the 12 months to October 2026. The biggest percentage code we've seen in that period was 50% off in November 2025, so the current 15% codes are typical for the brand; the biggest sale on record is the 40% off in October 2026 that's active now.
