For most irrigation-focused homes in the Seattle area, 450 gallons is a starter tank, not a full solution. It can work for light watering, but many homeowners find it runs dry after a few weeks of no rain, especially in a longer summer dry spell.
Product Water sizes storage using your roof area, local rainfall, and how much you actually plan to water, not just “what fits in the corner.” In many cases, that points closer to 1,000+ gallons or multiple linked tanks if you want real resilience instead of a token system.
Almost no one knows their roof water budget—how many gallons fall on their roof in a typical storm or year. A simple rule of thumb used by utilities is to multiply your roof footprint by rainfall depth to estimate total gallons.
Product Water builds on that idea with a roof-rain calculator that uses your roof size and local rainfall patterns to show how much water you could capture and how that translates into tank sizing. That’s the foundation of our Redirect and Store stages in the Product Water Method.
Yes. Many clients begin with one tank and add capacity later, especially after living through their first dry spell and realizing how quickly a small tank can empty. Product Water designs with expansion in mind—multi-tank layouts, hydraulic connections, and space planning—so adding a second or third tank is clean rather than a band-aid.
At the same time, we always show you what a right-sized system would look like up front, so you understand the trade-off between starting smaller now and having the capacity you’ll likely want long-term.
How you use the water is just as important as how much you store. High-pressure hoses and sprinklers can burn through a tank in days, which makes any system feel undersized, even when the storage is reasonable.
Product Water’s Manage & Use focus leans on low-pressure, high-efficiency approaches—like drip, soaker, and gravity-assist layouts—so each gallon does more work before it leaves your tank. To see how this works in practice, explore our Responsive Drip Irrigation system and 30% water savings case study .[file:1] This is where the value of good Redirect and Store decisions really shows up in your day-to-day experience.
The Product Water Method looks at your site as a rain system, not just a place to park a tank. We design in three linked stages: Redirect (move rain off the roof intelligently), Store (right-size and place your capacity), and Manage & Use (move and apply water with low-pressure, high-efficiency techniques).
This approach goes beyond the usual “downspout into a barrel” mindset by using hydraulic routing, multi-tank options, and smarter use practices to turn your roof into a reliable, flexible water source instead of a missed opportunity.
