Drought as the New Reality

Chris Maxwell-Gaines, P.E.

What this means for our Homes and Landscaping

Renewable Energy Roundup 2012, Fredericksburg, TX

• Integrated water conservation solutions

• Rainwater, Graywater, Drainage, Irrigation

• Design / Build

• Residential / Commercial

How do we interact with water

in our daily lives?

Where is the next revolution and

opportunity of water conservation

in the future?

Personal Habits

Water Usage

Water Fixtures + =

Personal Habits

Water Usage

Water Fixtures + =

Change current laws & regulations

Improve efficiency of fixtures and appliances

Change

personal habits

& cultural norms

to reduce demand

Indoor Water Conservation Standards

Future Conservation Gains will be Outdoors

Law of Diminishing Returns

Personal Habits

Water Usage

Water Fixtures + =

Change current laws & regulations

Improve efficiency of fixtures and appliances

Change

personal habits

& cultural norms

to reduce demand

Personal Habits

Water Usage

Water Fixtures + =

Change current laws & regulations

Improve efficiency of fixtures and appliances

Change

personal habits

& cultural norms

to reduce demand

Untapped sources of

conservation+

Personal Habits

Water Usage

Water Fixtures + =

There are Many Pieces to this Puzzle!

The Puzzle Pieces…

Keep Water Onsite

Reduce Irrigation Demand

Reduce Water Waste

Collect Auxiliary Water

Reuse Water

Keep Water Onsite

Typical Urban Water Balance Model

Precipitation

Municipal/Well Water

Other Stormwater

AC Condensate

Run-off

Wastewater (Black / Gray)

Your House and Property

Integrated Urban Water Balance Model

Precipitation

Municipal/Well Water

Other StormwaterWastewater (Black)

Rainwater/AC Harvesting

Graywater Reuse

Low Impact Development Strategies

Stormwater infiltration

Permeable pavement

RainGardens orBioretentionPonds

Reduce Irrigation Demand

Native, drought tolerant plants

Xeriscaping

Low-impact development BMPs

Synthetic grass

Reduce irrigation demand

Picture from July 2011 - $650 water bill

Urban Farming

Reduce Water Waste

Efficient Irrigation Practices?

Collect Auxiliary Water

Rainwater Math

___ in of rain X ___ roof sq ft X 0.623 gal/sq ft

“1 inch of rain on a 1,000 sq ft collection area

will yield 623 gallons”

Rainwater collection benefits

• Reduces storm water runoff

• Better for your lawn and garden plants

• Simple technology that is easy to maintain

• Recognizable as a green building technique

• Solution to on-site drainage problem

• Reduces effective impervious cover

Rainwater uses

• Outdoor water use– Irrigation of landscaping and lawns– Other outdoor uses

• Indoor, non-potable water use– Toilets, urinals, & clothes washing

machines

• Potable water supply– Filtration and disinfection required

• Most frequently asked question – tough to answer

• Water budgets are good start

• Collection surface size

• Two basic constraints: Physical space & Budget

System Sizing & Efficiency

Rainwater Supply vs. Irrigation Demand

Rainwater system typology“Dry” Connection:

Pipes drain completely

Easy system to install and maintain

Tank must be located close to collection surface

“Wet” Connection

Water remains in collection pipes

Gutter must be above tank inlet

Allows any location of storage tank

Rainwater Incentives

• COA provides a rebate up to $5,000 for rainwater collection systems

• Rainwater harvesting equipment is sales tax exempt in TX

• Hays County gives property tax exemption

• COA provides water quality credits

• LCRA provides impervious cover credits

Consider other auxiliary water sources

• AC Condensate

• Graywater

Reuse Water

Graywater reuse

Graywater

Bathroom sink

Shower/Bath tub

Clothes washer

Blackwater

Toilet

Kitchen sink

Dishwasher

State law: TX, NM, AZ, CA, UT, MT

TX: HB 2661 & SB 779, effective January 2005

Typical Indoor Water Use

Graywater reuse benefits

• Cascading water usage – water already paid for

• Minimal treatment required

• Accounts for about 40-50% of indoor water use

• No need to store graywater – constant production

• Detergents can be beneficial to plants – fertilizer

Graywater specifics

• No permit for domestic use of less than 400 gallons each day

• Can’t hold on to it

• 100% diversion capability

• No spray irrigation

• No indoor use

• System clearly labeled

www.watercache.com