Cleaning the pump

Half Dome – Yosemite Musing

So you got your new water filter pump. Good move – expensive but it should last for years. The waters in the Sierra are plagued with 2 intestinal parasites: Giardia and Cryptosporiduim. Teeny tiny little protozoa. The root is from E-Coli, which gets into the water from well, er, (can I say it?) – poop. Yes, think of all those deer, marmots, bears, mountain lions, coyotes, millipedes and people all over the park who drop their packages into streams and rivers. As they say “stuff happens.”  Iodine tablets do work but only on Giardia. Hmmm, good for emergencies but not for your mainline water treatment. If you are using other modern tablets, read them carefully to make sure the 2 offending critters are knocked out. Oh, you will feel fine – but in about a week, you will get a case of the “green apple 2-step.” (Can I say it?) Diarrhea. Anyway, back to the point found  in the title. When you get home, you need to flush out all the hitch-hiking bugs. Do this (read your user manual first):  Take a plastic water jug and cut the top open so both ends of your filter fit in. Then add a gallon of water and 2 tablespoons of ordinary bleach. Then pump for about 5 minutes to circulate the solution through your filter. Chlorine in bleach will kill any nescient protozoa. Then open up your filter and let it air day for a day out of the sun.

 pump 2


pump 3

If the filter itself has crud on it, wipe it gently with a soft toothbrush or sponge. Pack it all up and you are ready for your next Half Dome hike. When you pump your first bottle next time, let the initial cup or so flow out before putting the outlet into your bottle. This lets any settled residue out. One final thing, when yo use your pump in the field, keep the outlet end in a separate baggie. You don’t want ka-ka water getting on the “clean” end.

ERRATA: I mentioned a while back the Mt Whitney is the tallest Mt. in the lower 48. And I said Denali is the highest in the whole US. Then I knee jerked and called Whitney the 2nd highest. I got caught – there are many Alaskan peaks higher than 14,495’ My bad.

Unrelated thought worth quoting: “I read the news today oh, boy. Four thousand holes in Blackburn, Lancashire. And though the holes were rather small They had to count them all. Now they know how many holes it takes to fill the Albert Hall. I’d love to turn you on,” A day in the life, the Beatles

*Mr. Half Dome -Rick Deutsch –

About Mr Half Dome - Rick Deutsch

Mr Half Dome. Has written the only half dome hiking guide, One Best Hike: Yosemite's Half Dome. Has hiked it 31 times to day. Lives in San Jose, CA Available for presentations. Carpe Diem Experience, LLC
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5 Responses to Cleaning the pump

  1. mrhalfdome says:


    To each his own. I say why risk it? In addition to the real world “got sick” anecdotes I mentioned, I worked with a guy 10 yrs ago who got very sick wih malaise. He felt like crud and it dragged on for months. The doctors could not figure out what his issue was. Then he related that he was at Bridalveil Falls and opened his mouth and got a drink under the fall spray. Giardia was diagnosed. Roll the dice and take your chances.

    I know there is a Berkeley Prof who did a study like the one you mentioned. 10 more got the “treat it” result.



  2. YOSHIKER says:

    I have hiked Yosemite and the Sierra for 45 years, always drinking the water and never filtering it. Never had a problem, nor has anyone in my group. The park will always err on the side of caution and the filter manufacturers will say whatever it takes to get you to buy their products. A microbiologist has tested water at popular Sierra camping areas for 20 years and found the occurrence of water borne pathogens to be almost nil. I say why spend money on filters, carry unnecessary equipment, and spend hours pumping water? Wash your hands after you poop, enjoy the delicious taste of pure mountain spring water, and have one less thing to be uptight about in the wilderness.

  3. mrhalfdome says:

    Poop is poop. There are a ton of articles on Giardia including on the NPS site. There are three ways that giardiasis, the disease caused by ingesting Giardia cysts, can be contracted: contaminated water, contaminated food, and direct fecal-oral. I know a Ranger who told me he got Giardia from the “Little Spring” on the Half Dome trail. Ranger Dick Ewert told me he has had it 3 times from the Yosemite water. A friend told me his neighbor’s son died from it by not getting it treated. The EPA says that about 90% of all FRESH water on Earth is now contaminated with something. Some say you get it from poor hygiene habits. I’m not a Micro-biologist (although I play one on TV), I say why debate it? Filter it or roll the dice. I wear a seatbelt, though I never want to test it.


  4. Kathy says:

    Interesting, John, I was at a Ranger’s talk before a Ranger led hike in Yosemite and he told the folk to make sure and filter water because of Giardia…

  5. John says:

    Rick–I’d be interested in knowing why you say that the protozoa infest waters in the Sierra. We took an SMI guide up Whitney, and he informed us beforehand that the stomach bugs are born by cattle. Since there are no cattle around there, no bugs. We did 6 days in Yosemite, including Tuolumne, Conness/Saddlebag area, and 3 days in Whitney area; drank straight from springs, filtered nothing, no problemos. I’d be interested in real cases in the Sierra, because, as I say, the guides up there claim the waters are drinkable.

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