Weekly Watering Number | Regional Water Providers Consortium
Weekly Watering Number
Jul 11–17, 2024
Enter your zip code to get your number:

Smart Watering Tip:

Many plants were damaged in this past week’s heat wave, but with a few tips, your garden can bounce back. Remember: burned leaves don't necessarily mean that your plant is dead!

Watering Guidelines:

If your Weekly Watering Number looks higher than average for this time of year, that’s because it is! Higher temperatures and drier conditions from this past week’s extreme weather means we’ll have to water a bit more to keep our landscapes healthy this week.

Weekly Watering Number

Everyone can have a blue thumb – start watering smart today with the Weekly Watering Number! 

Here in the Portland metro area, we like to joke that summer officially starts July 5th. But, while summer weather may finally kick in then, we often start watering our lawns and gardens the first or second warm-ish spring day. And, we keep on watering them until the fall rains begin.

What many people don’t know is that established plants (those that have been in the ground a year or two) usually don’t need to be watered until the warmer temperatures set in and dry out our clay soil. In fact, spring can be a great time to conserve water!

That’s where the Weekly Watering Number (WWN) comes in. Sign up for the WWN and we'll tell you when to start watering and how much to water each week through mid-October. We will also send you a Weekly Tip, along with your WWN, throughout the watering season to help you use water efficiently outdoors. If you have questions about your subscription to our newsletter or meeting notices, or you would like to unsubscribe, email us.


The form is also available at this link.


How to get started with the Weekly Watering Number

Before you can start using the WWN, you will need to take 15 minutes to figure out how long it takes your watering system to water one inch. Don’t worry, this is a one-time thing! Once you have this information, you can use it adjust the amount of water you give your landscape or garden throughout the irrigation season.


How to use the Weekly Watering Number

Different plants have different water needs and you can use the WWN to tailor the amount of water you give to different plant types (e.g. lawns, perennials, vegetable, trees). See below for more information on how the WWN can be used for lawns and other types of plants.

The other key to watering efficiently is to adjust the amount you water as the weather changes throughout the irrigation season. For example, we’ll let you know if a rain storm or heat wave means you should change how much you water – and we will tell you how much of a change is needed.


Can I use the Weekly Watering Number for other types of plants?

Yes. The WWN is the amount of water in inches that your lawn will need each week. Different plants have different water needs, and you can adjust the Weekly Watering Number for different plant types with these general guidelines:

  • Lawns: 100% of WWN
  • Shrubs and Perennials: 50% of the WWN (newly planted plants may require more water)
  • Vegetables: 75% of the WWN (new starts may require more water)
  • Trees: The WWN is not recommended for trees, but that doesn’t mean that your trees don’t need water during the summer! Newly-planted trees need regular watering for up to the first couple of years, while established trees may need a deep soak or two in summer. We also recommend consulting with staff at local nurseries or arborists on the specific water needs of your trees since different plants need different things to help them thrive.


Why does the Weekly Watering Number change each week?

The WWN changes with local weather conditions. So, in the cooler, wetter spring it tends to be lower, and in the hotter drier summer it tends to be higher.


What does my zip code have to do with this?

Sometimes weather is warmer, cooler, wetter or dryer where you live than it is across town. We customize your WWN based on your specific zip code so that it is more accurate.


Where does the data for the Weekly Watering Number come from?

The Consortium contracts with a weather forecasting service to provide the data, including rain fall, evapotranspiration, solar radiation, needed to generate the WWN.


Why do you use historical data to create the Weekly Water Number?

The WWN is based on the previous week's weather (heat, rainfall, wind, etc). It is meant to replace any moisture that your plant's soil lost the previous week.