Tap to Toilet


tem C-2 for Tuesday’s regular Morro Bay City Council [June 28] meeting is regarding the AWSDA(Annual Water Supply and Demand Assesment) report that the Planning Commission just saw this week.  On page 448 of the staff report it says, “Injected SWP Water – With the anticipated construction of the WRF indirect potable reuse test injection well in July 2022, the City will have the ability to inject water into the Morro Basin to increase the amount of groundwater in storage that it can rely upon during the SWP Shutdown. The City anticipates injecting water starting in August/September 2022 and slowly building up a supplemental supply of water up until November 2022. The City can then utilize the additional groundwater placed into storage in Morro Basin until the SWP is back online in December 2022”.  This is illustrated in the graph on page 450 as the orange column. 

My comments:

The City starts showing this injected state water in the month of August but that is only when they begin injection but admittedly won’t be extracted until November when the state water is down for maintenance as it does each year.  Therefore, it cannot be considered as supply or available until November when they show it is actually needed.  What they don’t say is that since it is being put into the contaminated ground in the lower Morro Valley, it will need to be processed in the city’s reverse osmosis treatment plant before being put into the city’s water system.  Why on Earth would anyone in their right mind put that perfectly good, already treated drinking water into a contaminated groundwater basin and mix it with that crappy water that needs to be treated once again?  There must be a better place to inject this water.

The graph on page 451 which shows the reclaimed IPR (Indirect Potable Reuse) water only used in years 9, 15 & 16.  We have been repeatedly told that the reclaimed water will provide 80% of the town’s supply.   Have City leaders not be honest with the EPA and the SRF folks in order to get their financial assistance?  Those loans are predicated on utilizing recycled water most all of the time from here to eternity.  The EPA press release indicated 100%. Does this mean that the shiny new WRF dairy farm on the hill is really no more than a very expensive glorified wastewater treatment plant that will discharge the treated toilet water into the ocean once again?

Do you really understand 

“Toilet to Tap?”

The City of Morro Bay by the operation of their new WRF facility will be able to produce large quantities of highly purified, reverse osmosis derived water. The question is what to do with this very expensive, non-potable water. The City’s promise to the citizens is that they will provide it to them during water shortages to reduce their dependence on State water. That is easier said than done.

The phrase “toilet to tap” is generally used in a disparaging way to describe purified water from a sewage treatment facility intended for human consumption. The science on this subject is quite extensive and has resulted in laws and regulations to protect humans from poor practices. Reverse osmosis (RO) is currently the best way to achieve a high level of water purity from sewage, however this process has not been able meet the standards needed for long term human use. This is because such purified water does have small amounts of viruses and organic chemicals in it (the organic chemicals of particular interest are drugs, both ethical and illegal, and biological derivatives that are bioactive). Granted, the levels of impurities are small, but the number of them can be quite large, particularly from sewage sources. The long-term consumption of such low levels of biologically active materials is unknown, but regulations on exposing large segments of the public to them is universally prohibited.

The question then is how to remove these potentially hazardous materials from the RO water. This requires a different methodology from RO and oxidative treatment by either chlorination and/or ozonation. Currently the only approved way forward is to allow natural bacteria found in contained, percolating aquifers or large reservoirs to metabolize (eat) them. This generally requires a three-month residence time in such bodies of water before recovery of the RO water.

The City of Morro Bay is proposing to inject their RO water from the treatment of local raw sewage into an underground river in the Lower Morro Valley for a projected two-month residence time and then recover it through the wells in Lila-Kaiser Park. This has several key issues that need to be addressed. Firstly, no-one has ever used a subterranean stream, which is a non-percolating aquifer. This lack of precedence is disturbing and relies on the citizens of Morro Bay to be guinea pigs in this experiment. Secondly, the shorter than three-month residence time in the riverbed is certainly pushing any data that can be used as a clear comparison to the longer residence time data.

There is another major concern in the proposed purification of the WRF’s RO water and that relates to the wells they are going to be using to recover the water. These wells have been proven to be contaminated with raw sewage from the underground North Morro Bay sewage Collection system. This City testified to the Regional Water Control Board in 2014 that they did not need the water from these wells, so no restrictions were attached to the “useless” wells. In the interim, the City has not replaced the leaking sewer lines so there is no expectation the wells have miraculously rejected the underground sewage flow. This is disturbing, for two reasons. First, the City does use the contaminated water every year when the state water supply is interrupted for cleaning. Second, the supposedly cleaned up WRF RO water will be re-contaminated by using those wells during the recovery of the RO water. This will require another RO treatment and aquifer purification before being fit for human consumption. They would need a different aquifer to avoid contamination during recovery which is not possible if they are using contaminated wells. In fact, the contaminated soil may require for require decades to be decontaminated by natural means.

The bottom line is that there are tried and true ways to upgrade water from sewage treatment facilities to make it fit for human consumption. The methods being proposed by the City of Morro Bay are likely to fail to afford the citizens of Morro Bay with safe, potable water. Since RO water is way too expensive for agriculture, it needs to be used wisely or not made at all. The City will soon have an RO water facility that may only be useful for deterring salt-water intrusion into Morro Bay at considerable expense. It would be advisable to find a better way to use this expensive commodity if we are going to produce it.

Carole Truesdale 
Morro Bay

Editors note: To see the agenda and report, go to morrobayca.gov/ArchiveCenter/ViewFile/Item/5952 

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