Multi Family & Commercial

Overall, the drive for water re-use on Multi-Family developments is similar to residential:

Maintain a lush green landscape throughout summer, despite water restrictions and drought.
This maintains Resident Interest, Drive up appeal, and results in higher rental returns.

Reducing Irrigation Water Cost.

There is more than enough graywater and other alternate water sources available to completely avoid the use of potable water. Purely on water savings alone, payback of a single or multiple IrriGRAY systems is typically within 4 years.


Water Savings.

Substantial Federal finance incentives are available for saving water. Allocating 20% of the 10 basis point finance incentive is a key driver, providing $140,000 return over 10 years, with a starting incremental investment of $27,750.

Intangible Benefits

  • Automated Water Management and System Monitoring / Fault Reporting

  • LEED Points

  • Overall water conservation Public Relations boost

  • Reduced Maintenance costs (spray vs drip)

Focused Design

We have found developers and engineers have a tendency to imagine a single graywater re-use system managing all graywater and irrigation across the property. 

However, because the unit cost of IrriGRAY is relatively low, and the cost of attempting to plumb all required graywater fixtures to a single point of processing is very high, it simply makes far more sense economicaly to have 'focused' systems.

In this diagram, we show how a development can be broken into smaller sections, each having its own graywater collection and irrigation system.

Because of IrriGRAY's flexibility, Developers who wish to enhance and publicize green factors in their design and marketing can integrate additional water-reuse methods, such as Rainwater Harvesting, A/C Condensate, additional Storm Water detention and re-use, and more.

Limiting Graywater Collection

Each development is different, but the following universal rules apply:

  • Determine how much water is required to fully support irrigation needs

  • Determine which are the most efficient and cost effective methods of capturing this water (generally graywater)

In almost every case, there is far more graywater available than needed, and it is pointless capturing all graywater drain fixtures.

This substantially lessens plumbing costs. In this diagram, the red, green and purple sections are irrigated landscape sections. The full yellow building area may require all shower waste to be plumbed into IrriGRAY to support the Red and Purple areas, while only a small group of apartments is needed to support the green region.

Graywater from the yellow bounded building is not required at all.


We are often asked about the economics of Graywater Treatment Systems, for reusing graywater in commode and laundry water supply. At this stage, unless exceptional circumstances are in play, current and medium future technology is not justifiable. Click on this blog post for a detailed analysis of Graywater Treatment for Residential and Multi-Family / Commercial applications.


  • Green Building Certification Pricing Break (Fannie Mae / Freddie Mac) 10 bp pricing break, of which water is a contributive factor

  • Green Preservation Plus program (Fannie Mae / Freddie Mac) allows up to 85% LTV, lowered Debt Service Credit Ratio - up to 5 bp lower than standard rates, and access to property's equity amount equal to investments in efficiency

  • Value Creation via lower operation expenses and applied cap rates

Determining which incentives are most useful to your development, and the financial modelling involved can be complex. Please contact us with a description of your development and we can provide a detailed analysis.

Commercial Applications

Codes have changed significantly over the last few years, now allowing extensive reuse of alternate water sources for irrigation, such as AC Condensate, Foundation Drain, Graywater, Rainwater, Well water & More. 

AC Condensate is the easiest and simplest of all available alternate water sources, and for any sites with significant air turnover, AC Condensate as irrigation supply has a very fast ROI, as well as added benefits of landscape protection and 'Green PR'.

As an instant irrigation system - where alternate water is irrigated as soon as it is collected - IrriGRAY is inexpensive to install and provides substantial year on year savings.

Graywater in particular, previously seen as a nuisance and disposal cost center, provides opportunities of reduction in potable water cost, disposal cost, landscape preservation and Green PR.

Of course every site is different, but be assured IrriGRAY caters for virtually all scenarios, so contact us for a brief discussion and allow us to point you in the right direction.

Example, for a 400 unit development, where only graywater from 150 units is required.

  • Initial Incremental Investment: ($27,750)

  • Combined Benefit if property sold at 4 years: $320,000

  • Benefit if property sold at 10 years: $700,000

By any measure, these incentives alone (without considering any local or state incentives that may also be available) make graywater reuse for irrigation an extremely attractive proposition.

Hotel Laundry e.g. Super 8 Hotel California (50 rooms)

  • 600 gallons per day

  • 10,000 sf lawn

  • 5,000 sf beds

  • Landscape preservation

  • Potable Water Savings

  • Graywater Disposal Savings (reduced discharge fees, metered reduction)

High Volume Restaurants

Shop Strips

Large Buildings

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