Tag Archives: Seattle rainwater harvesting

Infrastructure, Rainwater Catchment

The Cost of Seattle Water

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The Cost of Seattle Water

The Seattle water system is a good one, provided by Seattle Public Utilities. But, as the demand grows with urban development and population, the cost of Seattle water will need to rise to support expansion.

A recent article by Gene Balk in the Seattle Times makes some interesting points.  Balk mentions “…bafflingly — drought-stricken Fresno, Calif., has some of the cheapest water in the nation. At a 50-gallon-per-person usage, a family of four would pay just $41.63 — less than one-quarter of the cost in soggy Seattle.”

Balk goes on to write: “Seattle has such high rates because we’ve invested more than most places in our water infrastructure in recent years. We relocated our reservoirs underground, in compliance with federal mandates, to keep our drinking water safe from contaminants. “

We can clearly see that it’s not the amount of Seattle water that is the generator of costs, it is the infrastructure required to convey and treat the water to potable standards.

Approximately 70 % of household water demand is for non potable usage. Irrigation, water closets, laundry, and wash down account for this non potable use. Rainwater collection can mitigate non potable use of city water and have a positive effect on our centralized water system and environment.

The commercial building owner and the home owner can enjoy healthy savings on future Seattle water bills by utilizing rainwater collection. Stormwater reduction could be significantly recognized through on site filtration if buildings and homes in the urban environment adopted rainwater collection .

Seattle is a progressive city in many ways and rainwater collection is part of that progression.

How-to, Rainwater Catchment

Ultraviolet Light Disinfection For Rainwater Harvesting

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This is the final post on “How to Build a Rainwater Collection System.  Click to see parts one, two, three, four, five, six, seven and eight of “How to Build a Rainwater Collection System”.

There will be additional posts that elaborate on some key points in the near future, so stay tuned (click the box below to receive new posts in your email inbox).

uv-lampThe final stage of treatment for a potable rainwater collection system is ultraviolet light disinfection (UV). Effectiveness of the UV system is determined by a few factors.  First, pre-filtration, which includes a sediment filter and a carbon filter that need to be upstream of the UV. This will help ensure the clarity of water entering the UV chamber, enabling the UV rays to penetrate the water stream.

When UV energy is absorbed by the reproductive mechanisms of bacteria and viruses, the genetic material is “rearranged” and can no longer reproduce,  with risk of disease eliminated.

There are 2 classifications of UV light determined by the dosage of the UV light itself, and a class “A” UV is the only class recommended for disinfection of rainwater collected from a rooftop.

The American Water Works Association describes a class A ultraviolet system as an effective method of disinfection for water that is not determined safe to drink. A class B ultraviolet system is only effective for water already deemed safe to drink – such as a water source already treated with chlorine.

An alarm and or solenoid valve for system fail safe is always a good idea to include with your UV system. This method will shut down the system or sound an alarm if a sensor determines the water turbidity (clarity) is not sufficient for proper UV absorption.

Ultraviolet light is a natural, cost effective environmentally safe method of disinfecting drinking water as long as it is properly maintained and the bulb is changed according to manufacturer’s recommendations.