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How to view NYC tap water copepods:
· The copepods that come out of the tap are dead, in almost all cases. It is believed that the prolonged exposure to chlorine, along with the rigorous journey through the delivery system, is the cause. Their lack of movement contributes to the difficulty in finding them.
· All of the types of copepods in our water are translucent. This makes it virtually impossible to spot them in a cup of water.
· The fact that some areas generally receive only small copepods further contributes to the difficulty in spotting them. In general, the size of copepods starts at ~0.1mm length for the larvae, and ranges up to 1.4 mm for adults. The average length is 0.8mm. Their thickness ranges from ~0.1mm to ~0.3mm.
· They are best viewed in a shallow bowl of clear plastic, with black background behind it. The antennae and tails of the larger copepods are discernable without magnification.
· Copepods can be found more easily by inspecting a spent filter cartridge. Alternately, a cloth placed at the tap (unfiltered, of course) will catch the copepods of the water that passes through it. The cloth should be carefully inverted into a shallow bowl of water, and the copepods shaken off into the water.

Bitul in processed products: (note: solids are not batul in liquids which can be filtered – see YD 104)
· In many instances, the copepods are emerging from the tap intact. The D. thomasi variety appears, almost all of the time, with all four ‘antennas’, 5 sets of feet, and two ‘tails’. Of the other varieties, S. pygmaeus often are missing the antennas, and M. edax almost always are missing the tail.
· However, the sorting of the water system creates scenarios where some areas will receive only parts of copepods.
· In most cases, the amount of copepods in the water easily outnumbers the general dirt, flocculent, and detritus that is in the water. Localized problems with water pipes may introduce greater amounts of detritus, but then it is often brown in color.
· Cooking the copepods does not ensure that they will disintegrate, although prolonged cooking will cause a significant number to break apart. In controlled experiments by this writer, 10 minutes of cooking left the copepods 100% complete, while a half-hour of cooking caused 50-60% of the copepods to completely disappear. The remaining D. thomasi copepods were completely intact. In experiments that simulated cooking accompanied with agitation (stirring), 30 minutes of cooking with stirring caused 80 -90% of the copepods to disappear. This is consistent with the observations of Poskim as found in many responsa (see, for example, Sh’T Rav P’alim IV #8).

Filters:
· Placing a cloth around the faucet tap will reduce the amount of copepods. However, almost invariably, some will come through. Exactly how many depends on the type of cloth and the frequency with which it is cleaned or changed. Therefore, a regular cloth, even if layered, is an option that is difficult to recommend. If a cloth is used, it should be a tight weave, and changed or cleaned often. Several layers of cloth are more effective than one layer.
· Water filters are generally effective, at least in reducing the likelihood of finding creatures to a “miut shaino matzui”, unlikely occurrence. Filters are generally marketed by micron level [lower micron number = more filtration]. A micron rating of 50 microns or smaller has been found to be sufficient. It is noteworthy to mention that micron ratings supplied are typically “nominal”, not absolute. This means that a 30 micron filter (for example) will filter out most particles 30 microns or larger. Some will get through. Typically, nominal ratings are for 85% efficiency, which means 15% of the particles that size do get through. Happily, as particle size increases, the efficiency increases as well, so that a 30-micron nominal is likely to be 99% effective for, say, 60-micron particles. Another issue with replaceable cartridges is the potential for bypass. This occurs when particulate passes between the filter cartridge and canister, bypassing filtration entirely. This is discussed in the following two points:
· The quality of design of the filter is more important than the micron rating of its filtering material. As with everything else, not all filters are constructed equally. As a case in point, some “canister” type filters (designed for installation under the sink or at the water main) were found, after a few weeks of use, to allow small numbers of whole copepods through. The filter cartridges inside these canisters were rated at 15 microns, but lacked rubber gaskets at the place where they join with the canister. This apparently allowed the ends of the filter material to soften, and copepods passed around the filter cartridge, rather than through it. Also, some filtering materials are stronger than others, and are less likely to rip. There are numerous brands available, and many options in types of materials.
· Mixing cartridges and canisters is not recommended. Each company’s canister can be slightly different in size. A filter cartridge from another company may not fit perfectly, and bypass might occur. Furthermore, even when using a cartridge and canister from the same company, it is critical to use items that are matched for each other. Experience has shown that in some instances, a 5 micron 10” cartridge meant for a slim housing (3/8” tread) will be virtually ineffective when placed in a wider housing (3/4” tread).
· Filter cartridges must be replaced promptly when clogged. This is indicated by a noticeable drop in water flow at the tap. If left in place, the increase in pressure on the clogged filter may rip the filtering material, resulting in bypass.
· Whole home (“point of entry” ) filters are installed on the water main of the building. It is important to note that it takes a few days’ usage to flush out the copepods from the pipes. These copepods had been attached to the bio-film on the inside of the building’s pipes, downstream of the filter. Therefore, water should not be considered clean immediately upon installing a whole home filter. (For the same reason, these filters should not be bypassed on Shabbos). Upon filter installation, it is prudent to drain or flush the hot water tank, via the outtake valve at the base of the tank. While it is difficult to completely clean a hot water tank, this will reduce the number of organisms present. [As an aside, in very infested areas, choosing a “better” brand of whole home filters is critical for another reason – some brands will become completely clogged within a week’s time! Better brands will last for months, even in infested areas.]
· Filters installed under the sink last for a very long time. As hot water is not used for cooking and drinking, it is sufficient to install a filter on the cold water supply. In this case, letting the cold water run for a short time before using it for drinking and cooking (to clear out the faucet from possible organisms deposited by hot water use) is recommended, but not required. If one would like to be absolutely certain that no copepods make it out of the tap, they should install filters (of a reputable company) on both the hot and cold water supply.
· If installing a filter for the hot water supply as well, care should be taken to install a filter cartridge rated for hot water.
· Filters that affix to the end of the tap generally require frequent maintenance, due to the small surface area available for filtration. They also produce a weak flow of water.
· For copepod filtration, a filter between 5 – 50 microns is appropriate. Filters that are rated below that (one micron or half micron filters) are significantly more expensive, and while they may offer health benefits, they are an overkill with regard to copepod filtration. [Filters that use a carbon block or ceramic disk generally fit into this category. All filters that claim to reduce microbial cysts such as Giardia and Cryptosporidium are in this category].

Practical issues:
· Copepods are water creatures, and tend to stay with the water rather than stick to surfaces. This is especially true regarding a strong current of water.
· Dishwashers may be used without any filtration. Even when fed with infested water, testing has shown that copepods do not remain on the dishes or cutlery.
· Dishes may be hand washed in unfiltered water if allowed to drip dry without pools of water on them. If dishes were left to dry with pools of water on them, rubbing the dish’s surface with a towel will remove any residual organisms.
· Research is still being done on washing produce. It is noteworthy to mention that the original discovery of these water creatures by an individual who washed and checked his Alei Katif lettuce is not relevant to this question. The reason is that this individual checked the rinse water for bugs, not the lettuce.
· Cooking water for a short time has no effect on copepods. However, as the cooking time is prolonged, the amount of copepods that disintegrate and disappear increases. Cooking for half-hour generally eliminates half of them. Cooking accompanied by stirring or agitation significantly increases the reduction of copepods even more. See above, ‘Bitul in processed products’ for more details.

The reservoirs:
· The copepods have been found to live in all of the reservoirs that supply NYC, although some reservoirs have more than others. [Studies on the reservoir’s zooplankton population were done by the DEP in 1994 and 1995, as well as recently].
· The fast moving rivers and creeks that supply the reservoirs do not harbor the copepods that are present in our water.
· The Croton reservoir system, located in Westchester, supplies parts of Manhattan (including all of lower Manhattan, East and West Villages, Gramercy Park, Kips Bay, Chelsea, Clinton, East Harlem, Harlem, and Inwood) and southern and eastern portions of the Bronx. Aside from crustaceans, it has a documented history of midge fly larvae infestation. NYC is required by Federal law to filter Croton water. However, construction of a filtration plant for Croton is still in the planning stages, and is not expected to be completed before 2010. [Source: DEP publication, May 23, 2003, by Salome Freud].
· The remaining sections of the city receive water from the Catskill and Delaware reservoir systems. These reservoir systems deposit water into Kensico reservoir, located near White Plains, NY. From there, some water is further deposited into Hillview reservoir, a man-made reservoir near Yonkers, while most water enters the city distribution tunnels directly from Kensico. A small section of Queens also receives groundwater, but it is mixed with water from Kensico.
· Kensico reservoir is almost entirely (>95%) filled with water supplied from the upstate aqueducts. It has its own endemic copepod population. Hillview is completely artificial (no natural intake of water), and may have an endemic copepod population as well.

Other municipalities:
· Municipalities obtain water either from surface water (i.e. reservoirs, lakes, and rivers) or groundwater (wells and aquifers). Groundwater lacks many of the organisms found in surface water. Copepods are found in groundwater, but their size and numbers are significantly smaller.
There are 7,400 surface water systems in the United States, of which 7,310 have filtration plants. Municipal filtration, if properly maintained, will successfully remove copepods and related organisms from the water, to a level acceptable in halacha. Of the 90 systems that do not filter their water, most serve a very small population (<10,000). Aside from New York City, Boston and Seattle are examples of large cities whose water supplies are (at least in part) not filtered.