RainSave
The Journal
How Much Rain Can You Actually Harvest From Your Roof?
The math behind rainwater harvesting is simpler than it looks — a fixed conversion constant, your roof's footprint, and local rainfall are all you need to get a real number.
First-Flush Diverters Explained: Why the First Few Gallons Matter
The first water off any roof carries the dust, pollen, bird droppings, and grit that built up since the last rain. A first-flush diverter routes that dirty water away before it reaches your storage — here's how to size one.
A Home Water Audit: Where Does It All Actually Go?
Most households have a rough sense that showers and toilets use a lot of water, but few can say by how much. A simple room-by-room audit turns that hunch into real numbers you can act on.
The True Cost of a Dripping Faucet
A faucet that drips once a second looks like nothing. Run the numbers over a year and it stops looking like nothing — here's the arithmetic and why fixing it is almost always worth ten minutes with a wrench.
How Much (and How Often) Should You Really Water Your Lawn?
The '1 inch a week' rule is a good starting point, but a fixed schedule ignores your soil, your sprinkler's real output, and your climate. Here's how to build a schedule around actual measurements instead of guesswork.
Greywater 101: What You Can (and Can't) Safely Reuse
Not all household wastewater is created equal. Understanding the difference between greywater and blackwater — and what greywater can realistically be used for — is the first step before considering any reuse system.
Low-Flow Fixtures: Which Upgrades Actually Pay for Themselves
Not every water-saving fixture swap is equally worth it. Comparing the gallons saved per fixture against typical replacement cost shows which upgrades pay back fastest — and which barely move the needle.
Roof Material, Slope, and Runoff: How Much Do They Really Change Your Harvest?
The 0.623 gallons-per-square-foot constant never changes, but the runoff coefficient standing next to it in the formula can easily swing your harvest estimate by 25% or more. Here's what actually moves that number.
How Big a Rain Barrel (or Cistern) Do You Actually Need?
Bigger storage isn't automatically better. The right size sits at the overlap between how much your roof can realistically harvest and how much your garden can realistically use — here's how to find that overlap with real numbers.
How Much Is That Leak Really Costing? Translating Any Drip or Trickle Into Real Numbers
A dripping faucet isn't the only leak worth timing. A running toilet, a slow pipe leak, or a trickling hose bib all translate into the same gallons-and-dollars math — here's how to find, time, and add them all up.
Watering by Plant and Season: A Practical Guide Beyond 'One Inch a Week'
A lawn, a vegetable bed, and a newly planted shrub border don't want the same amount of water at the same time of year. Here's how the target itself should shift, with worked numbers for each.
Greywater Systems, Done Safely and Legally: What to Know Before You Build One
Greywater reuse is one of the most useful, and most misunderstood, water-saving projects a household can take on. Here's how simple systems actually work, why storage is the wrong instinct, and how to find out what's actually allowed where you live.