Cisterns & Storms/H...
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Cisterns & Storms/Hurricanes

Posts: 713
Honorable Member
Topic starter

A local and I talked at Kmart today about the possibility of a storm - she was headed home on lunch to make sure everything was okay since she wouldn't get home until after dark - and she told me something I have never heard in the past two years, so someone help me...

That if there is a LOT of rain and high winds the air sort of sucks up the top layer of the ocean and mixes it with the rain...and that therefore you should turn your cistern off in order to keep it from being contaminated with sea water? Does that apply if you are high on a hill as well, or is this even right?

...doesn't even make sense to turn off your cistern? So...I guess we're talking about undoing the drain thing-ys....all of them? We have one that there is no way a mocko jumbie on a ladder could reach...I'd like to add we are at approximately 360 feet elevation - I don't know if that matters - center island above the Botanical Gardens on STX.

Maybe I misunderstood - it's a good trivia question for the future...I mentioned it to someone else and they had heard the same thing. Just wondering. May not need it this time around, but sometime...

Thanks, ya'll...just didn't know about this one.

Posted : August 1, 2006 6:33 pm
Posts: 545
Honorable Member


After TS Jeanne came through in 2004, I don't recall any problems with cistern contamination with any foreign matter, including salt water. This was also before we installed a better gutter system that has filters and shut off valves.

Great question to hoping those with years of storm experience reply.


Posted : August 1, 2006 6:59 pm
Posts: 3030

Hello Becky & HipCrip,

I don't think everyone does it but some do. Part of my experience with hurricane preparations has been putting a large sponge in the intake area of the roof to prevent stuff from entering the pipes/cistern. When I questioned the logic it was along the lines of more dirt/dust/particles/leaves. I remember one time we didn't do it and the intake area, which has a screen over the pipe, was filled with leaves jammed in there. The screen of course prevented leaves from getting in to some degree, but I am sure some smaller pieces must have fallen in all the same. I don't recall the water tasting any different, but we did boil it before use for several weeks thereafter (don't remember how long). The method might differ depending on what sort of set up you have, and again I don't think everyone does this. During a storm that is passing a distance away but affecting the islands with bands of rain and not much wind, well thats a great opportunity to fill up the cistern.


Posted : August 1, 2006 9:12 pm
Posts: 2259
Noble Member

They say so but I have never done it. Never noticed any difference in the water that was collected.


Posted : August 1, 2006 9:24 pm
Posts: 545
Honorable Member

Great idea with the sponge, Islander. It just reminded me of the spongy products they sell up north to protect gutters from getting clogged up with leaves and debris, especially in the fall.

Ronnie, thanks for adding your experience.

I value both of your opinions/advice a lot!


Posted : August 1, 2006 9:39 pm
Posts: 859
Prominent Member

My present cistern already full from the last weather that came through.

Hugo and Marilyn both gone through in same STT location (not present place) and no problems but have aways drunk bottled water anyway. Post-hurricane always a good idea to get up there and check the intake, clear it of debris, then chlorinate cistern as usual just to be sure.

Posted : August 1, 2006 10:13 pm
Posts: 713
Honorable Member
Topic starter

Thanks - 'ppreciate everyone's help!

Posted : August 1, 2006 10:30 pm
Posts: 249
Estimable Member

Just a question as to whether or not people use the gutter systems there. By what I mean: It is a cap fitted over the eavestrough to prevent the leaves and sticks and other large debris from getting into the eaves and clogging up the gutters. We live in a heavily wooded area and neither of us wanted to get up on the second floor roof or climb the ladder to clean it (twice to three times a year). We had the caps put on and they work out wonderfully. Could help to keep the intakes clean and free of the large debris.

Posted : August 2, 2006 10:02 am
Posts: 12
Active Member

After reading references to cisterns on St. Thomas, I started doing a little looking around the Internet and found a reference to 'roof washer'. I've never lived off of, or even had a cistern, looked like an interesting setup.

Picture here ----->

Full information on this page ----->


Posted : August 4, 2006 2:25 am
Posts: 859
Prominent Member


Interesting reference but the whole set-up looks rather complicated and seems more compatible with an area where although "city" tapped water is the norm, this would be an alternative of diverting roof water into an external cistern and rendering it potable by a series of filters.

Houses in the islands are built with cisterns in situ - they're actually the FIRST things to be built.

But getting back to the various posts, I did make a bit of a mea culpa where hurricanes are concerned which is dependent on the type of construction and water catchment that one has. During Hugo and Marilyn, there were gutters and I DID disconnect the downspout when the s*** started hitting the fan on both occasions. The pre-rain had anyway assured me that the cistern was pretty full by that time and it was an easy disconnect. When the main thrust was over and the debris wasn't flying, I reconnected the downspout to take advantage of the aftermath rain.

Now my business has a flat concrete roof, no gutters and all the rain just goes through a central downspout in the middle of the roof. A few minor hurricanes since I've been in this location and many tropical storms and squalls with downpouring rain but I've done nothing and never had a problem insofar as potability is concerned. 6oz of chlorine bleach per 1,000 gallons of water is the recommended doseage, I just play it by ear and throw in what I "feel" is right and dependent upon how much water is in the cistern.

Years now since I got a "baddie" from the local testing people who come out here once a month in accordance with the local laws (don't get nervous, I'm commercial, not residential so the EPA folks aren't going to come charging after you!) But you should do the same basic chlorination once a month unless you have some fancy UVI or other fltration system in situ.

I don't know about those "caps," Eve. Think we're talking apples and whatever here. We rely on rain to fill our cisterns and I think you're talking about somewhere where you have access to city water and your gutters take the rain off the roof and then gush it out wherever. Gutter caps here would certainly impede debris getting in there but, down here, they'd impede water flow into our cisterns. Which is why we probably don't have them! Viable point, though, Eve. Cheers!

Posted : August 4, 2006 4:15 am
Posts: 545
Honorable Member


Unlike STT Resident's central roof pipe (a very nifty concept), the roof on our house drains into a series of 4-6" PVC piping that have mesh screens at the intake sites for blocking out the debris. Once in the pipes, the water is fully enclosed all the way to the cistern. There it goes through a filter.

To be honest about our ignorance/risk taking, we didn't even realize until well more than a year after we moved that it is recommended that you add bleach to the cisterns on a regular basis. As we had never had a problem with taste or potability, we decided to leave a good thing alone and still haven't been bleaching. (And still have had no problems.)

It probably helps that we also put on "caps" that stop the collection of rainwater as part of our hurricane prep process, done as we put up the window coverings, to avoid contaminated water and/or cistern overfilling during the height of any storm that comes our way (which we've happily and gratefully managed to avoid so far -- may that trend continue). I'm not sure if I read this on these boards or in the Hurricane Hugo book I read last year, but the firsthand accounts of cistern covers exploding off and even more water gushing into your living space, and cistern walls in the safe areas in some homes collapsing from the enormous amount of rain generated scared us into capping until the after storm, no matter how low the cistern levels are. After all, the last thing you'd want to do is try to go outside to turn off the drainage system in the middle of a hurricane.


Posted : August 4, 2006 5:08 am
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