Editor's note: This is a three-part series on water investing. Click here for Part One, and here for Part Two.

Part III: From Management to Treatment

Management

The companies here break down into two convenient categories. Most make sensor-activated computer systems that control and manage watering by studying weather patterns, soil moisture, soil radiation and other factors. Then there are a handful of companies, such as Vidler Water, that specialize in evaluating and selling water rights. Vidler often draws enthusiastic crowds at green tech conferences. Companies to watch include:

HydroPoint Data Systems is the granddaddy of computerized water management. The company raised $19 million in a Series C late last year and has been aggressively marketing itself.

PureSense surfaced from the Wet Incubator at Fresno State. The company provides a multi-signal sensor and watering system and sells it as a service. It raised $4.5 million earlier this year.

Accuwater has said it can achieve payback in water conservation in close to 15 months.

Treatment

The goal here is to take infected and/or dirty water and re-use it immediately for commercial purposes or provide the first stages of treatment for ultimate human re-use. The companies can be divided into two general categories.

A. Industrial Equipment and Services
Altela takes waste streams from refineries and industrial plants and cycles it through a unit that generates an evaporation-condensation cycle. An entire unit that can process 250 gallons of water a day fits into a 20-foot by 40-foot shipping container, the company says. It is more energy efficient than earlier attempts. The recovered water is then used in plant operations again.

Formerly known as H2Oil Recovery Services, 212 Resources (named after the boiling point of water) provides water purification services and recovers valuable hydrocarbons in the water stream. Has signed service agreements with Chevron, BP and others.

The Israeli-born BioPetroClean has raised over $8 million in VC funds. It performs similar services as Altela and 212 Resources but it employs bacteria to clean industrial water.  Scientists examine wastewater and compose a site-specific cleansing bacteria cocktail.

ClearWater Compliance Services specializes in services to prevent the release of water runoff from construction and other heavy equipment sites as well as some treatment. Raised $25 million from Plainview Asset Management last year. It bought KI Environmental in Canada in July.

EcoSphere has created a cargo container-sized ozone system for shipyards, plants and emergency sites. The high pressures generated by the system also make it useful for treating water at natural gas wells.

B. Municipal Purification
AqWise trades in municipal or agricultural water treatment. Polymer nodules create surface area for bacteria in treatment ponds. Increased surface area cuts down on the real estate required for treatment ponds.

In research projects at, among other places, the University of Copenhagen, scientists are creating slow-flow filters that eliminate particles through gravity. The water passes at a rate of a cubic meter every one or two minutes. It does not eliminate biological material.

Testing and Monitoring

Michigan's Sensicore raised several million in VC funds since 2000 to commercialize a chip that monitored water quality. It had difficulty landing customers. But in April General Electric bought it.