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mugaliens
2007-Nov-01, 06:56 AM
As an avid snorkler/diver, and a long-time fan of anything having to do with the ecology of our rivers and oceans, I decided this morning to browse Wikipedia and came across a brief mention of greywater (http://en.wikipedia.org/wiki/Greywater).

I thought, "what in the world is greywater?"

Then I remembered the time I'd rented a camping trailer, and that we had two holding tanks, one for greywater, and one for blackwater (http://en.wikipedia.org/wiki/Blackwater_%28waste%29) (human sewage).

Most waste management systems simply combine the graywater with sewage, and all goes to the sewage treatment (http://en.wikipedia.org/wiki/Sewage_treatment)facility.

The thing about greywater that I found most interesting is this quote from Wikipedia:


The majority of greywater ends up as effluent in rivers and oceans in this way. Despite treatment, this arguably results in greater contamination of natural waters, as the natural purification capacity of surface water is millions of times less than that of soil. Simply dumping greywater on the soil, from an ecological standpoint, is less damaging than sending highly treated greywater directly into natural waters.

So why aren't we using greywater for irrigation, or at the very least pumping it into forests for increasing tree growth, where the high biological activity in the woods will do an even better job of breaking it down before it reaches the rivers than open soil, instead of simply pumping it directly into the rivers like we're doing now?

I understand water supply and waste management systems can be expensive. Right now, we simply have one supply line (clean, fresh potable water) and one waste line (a mix of greywater and blackwater).

Having four lines, instead of two, would indeed be more expensive. Yet I do know that many farms irrigate directly from rivers, avoiding the cost of water treatment. Some have in-home treatment (pre-filters, such as back-flushable sand filters) followed by fibrous (cheap, disposable), then RO filters (expensive, disposable). Each stage minimizes the cost of the next, more expensive stage. Many homes in the US use septic systems, where the waste is collected in tanks then gradually released back into the ground, after going through a natural decomposition process.

I'm simply wondering if we can do a better job at dispersing the treated sewage rather than simply releasing it directly back into the rivers, where it causes the most environmental pollution to our waterways and oceans.

I know cost is a factor, but what's the cost of us continuing this environmentally harmful practice? Increased disease downstream? More beaches closed due to unacceptably high levels of bacteria? Red tide blooms which kill millions of fish (like that's not an environmental mess) and contaminate fishing and shellfishing areas? Coral reefs dying off due to still as yet undetermined causes?

From what I gather, our topside world is a bit hardier than our underwater world. Yet so much of human food comes from various sources in our oceans.

I just wonder why we're not doing a better job at reducing our impact on our underwater world.

Ronald Brak
2007-Nov-01, 07:52 AM
In some places in Australia people drink sewage. After it's been treated that is. As there are no seperate greywater/sewage pipes, it all goes into sewage and then gets treated. At my parents old house they had no piped water (or town water as we call it) and they had a greywater system that they would use to water the garden. Of course greywater can be used for more than just gardens. For exapmple water from baths and showers and washing clothes can be used to flush toilets.

I understand that water is very expensive in California and I'm wondering how popular rain water tanks and greywater systems are there?

mugaliens
2007-Nov-01, 04:50 PM
That's a neat idea, Ronald - using greywater from baths and showers to flush toilets. Probably keep them a bit cleaner, too.

It's ideas like this, along with stopping distributing greywater directly into waterways and instead using it for land and forest irrigation which will help prevent wasting good, fresh river water, and will help keep from contaminating more river water.

Trakar
2007-Nov-01, 05:22 PM
<snip of many good and accurate observations and considerations>

I just wonder why we're not doing a better job at reducing our impact on our underwater world.

I suspect that a large part of the problem revolves around the expenses necessary to run and maintain multiple plumbing and water handling systems. You have to consider that most grey water also contains all of the household chemicals employed, and frequently at least some sewage. Drain water, unfortunately also gets motor oil spills, anti-freeze, lawn and pool chemicals, pesticides, etc. Because we don't have distinct drainage and plumbing systems and the requisite disipline to keep some fluids entirely out of these systems and other substances only in the system in which they should be.

Granted we should and could be doing much better than we are, and diverting and minimally treating storm water and grey water and using it for irrigation may be a big step that we should encourage a lot more of, but it really, and generally isn't as simple an issue as it is often portrayed.