How much water does a garden or lawn need?

Tools for Assessing Water Needs: "Water Auditing"

A water audit is pretty much precisely what it indicates. In essence, one tries to assess water usage over a period of time, simply put. Now, this can be achieved in a wide number of ways: If you have irrigation up and running, an overview of the nozzle sizes and expected rate of flow will necessitate a simple mathematical chore of adding up all the nozzles, their frequency of occurrence, the time they spend running and their capacity at a certain pressure reading. These facts and figures are exceedingly easy to find.

For example, I use "Rainbird" products almost exclusively. It is a hugely common name internationally in irrigation. I use them because once an installer opts for a brand of irrigation with all its intricacies and uniqueness, it simply makes life easier than crossing things with competing systems with little differences in performance, yet huge differences in the physical parts and make up. "Toro", for example, is undoubtedly as good a product, yet they have a different nozzle and other differences that complicate any idea of mixing systems. It is the same with "Nelson". There are many ways to irrigate - none better than the other, but simplicity generally requires using the same products throughout a system.

This long-winded explanation was only necessary for the practical reasons of choosing a system and then staying with it. However - another reason for specifying the name recognition of products deals with their catalogs, where they will give the specifications on how these parts perform. This page shows a chart with these amounts, identified by the arcs and radii of all spraying nozzles, while yet others display the characteristics and specs dealing with the larger varieties of heads and nozzles of a "rotary" (larger) characteristic.

What these informative charts tell us is how much water is sent through the sprinklers per minute. Why is this informative? Because with this information, we are now able to total the exact amount of water we use daily, weekly, monthly or yearly. It is entirely possible to "audit" exactly how much water we use for our lawns and garden, down to the last gallon.

For those of us who rely on hoses and, say, oscillating sprinklers, or even using hand watering methods, a simple glance at the clock prior to turning on the hose and then recording it's cessation is all we need. It is quite simple to determine how much water comes out of a hose because it fulfills a preset formula based on size. Another way of determining how much water we use through our hoses is to grab a 19 litre (5 gallons) pail and fill it as rapidly as possible from the hose. The number of seconds or minutes it takes to fill a 5-gallon pail can be extrapolated over larger chunks of time. For example, if it takes 30 seconds to fill, then there is 10 gallons a minute going through the hose. This is all math and all quite do able for anyone. The real question, in the end, is what we do with the water.