Understanding Water Conservation
+1 805-541-1003


100% - 1 votes

Understanding Water Conservation

Apr 19, 2019
Video Length:  56:55
Presented By:  Gregg Roesink

Water conservation is a growing topic in our industry. Fueled by concerns about population growth and water supply, states and communities are implementing legislature to manage water usage. Gregg Roesink from Hunter will discuss California water restriction and regulation for sustainable irrigation and planting design. He'll present a responsible approach to design and go over the use of proven water-saving components in your projects.

Webinar Attachments:
MAWA-ETWU Calculator.xlsm
LandFX-Hunter Water Conservation Final.pdf

Webinar Contents:

Note: The following catalog of content covered in this webinar is time stamped to allow you to follow along or skip to sections of the video that are relevant to your questions. You can also search for content on this page using the FIND command in your browser (CTRL + F in Windows, Command + F in Mac OS.)


  • Intro
  • Common Terms & Water Restrictions and Regulations
  • Designing Responsibly

0:000 – 4:49: Intro & TOC

Water Waste Plagues Our Industry (2:33)

  • Water is a limited natural resource.
  • Availability should always be a concern.
  • Water users/consumers often don’t think about the issue.
  • Installing efficient irrigation systems is important.
  • Learning about “smart” water practices is becoming increasingly important.

4:50 – 30:09: Common Terms & Water Restrictions and Regulations

Distribution uniformity (DU) (5:47):

The measure of how evenly water is applied across a given area.


Evapotranspiration (ET) (7:04):

The science if estimating how much moisture the plants and soil have lost due to weather conditions – used to calculate irrigation amounts.


Reference ET (ETo) (8:10):

ET of a large field of well-watered grass.


Crop ET (ETc) (9:05):

ET with reference to crop coefficient.


Water Use Classification of Landscape Species (WUCOLS) (9:51):

  • Managed by the University of California Division of Agriculture and Natural Resources (funded by NWR)
  • WUCOLS IV provides evaluations of the irrigation water needs for more than 3,500 taxonomic plant groups (taxa) used in California landscapes.


California Irrigation Management Information System (CIMIS) (10:35):

  • CIMIS is an integrated network of more than 140 automated active weather stations located throughout California.
  • Reference evapotranspiration (ETo) is calculated and stored in a database along with the collected climatic data.


AB 1881 (11:00)

  • Approved in 2006 by Governor Jerry Brown
  • Quotes legislation back to 1991
  • Beginning of strict water regulation in California


Model Water Efficient Landscape Ordinance (MWELO) (11:50):

  • Specific to landscape water use
  • Most recently updated in 2015 (as of 2019)
  • Scheduled to be updated soon, at time of webinar presentation (April 2019)


Maximum applied water allowance (MAWA) (12:27):

This formula is used to determine the amount of water a project is allowed to use for landscape purposes.


MAWA example (residential property in Fresno, CA) (14:05)


Estimated total water use (ETWA) (15:47):

This formula is used to calculate the estimated amount of water used in the landscape area.


ETWU example (16:45)


MAWA/ETWU relationship (19:13)

  • ETWU must be a smaller number than MAWA.
  • Adjust plant material or irrigation application type to conform.


Question: Why is drip irrigation considered only slightly more efficient than overhead irrigation (0.81 to 0.75)? (21:03)

Answer: The efficiency of a drip system will depend on factors such as which equipment it uses, how densely the landscape is laid out, whether you use point source or inline, or subsurface or on-surface. Therefore, the number has been generalized at 0.81 to be on the lower end of the spectrum. In actuality, drip irrigation will typically be up in the 0.9 region of efficiency. Also, 0.75 may be a bit generous for overhead irrigation.


Question: Which head types are included in the overhead category in this context? (23:55)

Answer: Sprays are not included because they simply cannot reach this level of efficiency. The overhead category mostly consist of high-efficiency rotary type nozzles or gear-driven rotors.


Question: As we factor in these calculations, how are wet and dry years factored in? (24:35)

Answer: The reference information is all based on historical ET directly from CIMIS.


Question: Which counties or cities have these requirements? Why do some municipalities have the requirements while other do not? (25:50)

Answer: California requires each county and city to apply this model ordinance or something more stringent. Therefore, each city or county will have different requirements, but they need to be equal to or more stringent than the state requirement. If an area has not adopted these ordinances, it will be out of compliance.


Question: What is the method of identifying a plant factor that is within the range of 0.4 to 0.6?

Answer: Typically, you can go by sun exposure. A full sun exposure region would be on the lower end, and a moderate sun exposure region would be on the higher end. If you’re juggling between two plants in the same zone, err on the higher side.

30:10 – end: Designing Responsibly

  • Be selective with turf areas.
  • Keep turf only where it’s practical.


Keeping a water conservation checklist (31:32)


Spec mulch in planters. (32:35)

  • Keeps moisture in the soil
  • Manage soil temperature
  • Act as a weed barrier
  • Gives nutrients back to the plants
  • Covers dripline


Smart control and sensor technology (33:27)

Smart controllers estimate of measure depletion of available plant soil moisture in order to operate an irrigation system, replenishing water as needed while minimizing excess water use.


Irrigating to plant needs (34:40)


Seasonal adjustment (36:20)

  • 100% = setting run times for midsummer (peak demand time of the year)
  • 70% = run times adjusted for actual conditions


Soil moisture sensors (38:00)


Combining a soil moisture sensor and weather sensor: the best of both worlds (38:49)


Web-based Wi-Fi control (39:55)


Flow sensing (41:30)

Flow sensors track water use and stop breaks in their tracks.


Precipitation vs. infiltration rates (42:42)

MP Rotators deliver water at a slower rate than soils can absorb.


Precipitation rates:

  • Sprays (average): 1.6 inches/hour
  • MP800 Series: 0.8 inches/hour
  • Standard MP Rotator: 0.4 inches/hour


Water savings in pressure regulation (44:52)


Water usage test performed with the Pro-Spray PRS 30-FloGuard with the nozzle removed (45:15):

  • 30 GPM (113.6 l/m)
  • 6 GPM (22.7 l/m)

  • 0.5 GPM (1.9 l/m)


Drip irrigation (47:12)

Converting areas to drip irrigation can result in up to 70% in water savings. Drip irrigation provides slow, even watering for close-in coverage right where it’s needed – with no overspray onto the hardscape.


Drip & micro-irrigation (49:03)

  • Eco-Mat®
  • Eco-Wrap®
  • HDL: In-Line Drip
  • Point Source


Hunter resources (50:00)


How to apply these standards to another state or location (52:25)


Question: Does an existing pool have a factor of 1? (55:00)

Answer: Yes.


Presenter info:

Gregg Roesink, CLIA, CIT, LICT, QWEL, RWSS

Product Training Specialist, Hunter

Direct: +1 760-591-7135

Mobile: +1 619-743-2766

Technical Services: +1 800-733-2823


Log in to landfx.com: