The Frugal Off Grid Water Calculator

Simple water calculators I personally use when planning off-grid systems. No guesswork, no fluff. Just clean numbers you can actually use.

Video overview from my homestead

If you are new to rainwater harvesting, watch the video first so the numbers make sense in real life. Then come back here and run your own roof size and rainfall so you can plan with reality instead of hope.

If you want to see one of the cheapest storage options I’ve used, this is the cistern writeup: How to build a cheap water cistern for rainwater storage

Rainwater Harvesting Calculator

Estimate how much rainwater you can collect from a roof based on surface area and annual rainfall.




Enter your numbers and hit Calculate.

Note: This is a rough estimate. Real collection depends on roof material, gutters, first-flush, and losses.

Pond and Underground Cistern Calculator

Estimate how many gallons will fit in a pond or underground cistern based on simple dimensions.




Enter your numbers and hit Calculate.

Liner Size Calculator

Estimate liner size for pond liner or repurposed billboard vinyl. Uses your pond or cistern dimensions above.


Enter length, width, depth above, then calculate liner size.

If you’re new to off-grid living and want the full step-by-step path, start here: Off-Grid Living for Beginners

If you want the calmer long-form stuff, the Library is here: The Frugal Off Grid Library

 

Contact form