Can someone tell me how much Cal to use in a cisterna, say for 5000 litres of water?
I know that I have to mix it to a paste before adding and then wait a few days before drinking any water (all a bit vague) but my main question is how much to add.
Any (sound) advice much appreciated.
Thanks

Water treatment tips...

http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/wqe11319/$FILE/cisternstorage.pdf

http://www.thewatertreatments.com/wastewater-sewage-treatment/coagulation-types/

Hillbilly forum.

http://www.backwoodshome.com/forum/vb/archive/index.php/t-23066.html

http://www.wind-sun.com/ForumVB/showthread.php?12583-Keeping-water-fresh

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Thanks for the links. Interesting and the most common is the use of Chlorine in the water. I do that at present with the tablets designed for swimming pools and a carbon filter to fix the taste. However water then goes to a septic tank (which won't like any chlorine) and plants which likewise could do without the chlorine.
This all brings me back to looking at the local traditional way of using lime, but how much?

wrote on Aug 9^th, 2012 at 3:36pm:

Thanks for the links. Interesting and the most common is the use of Chlorine in the water. I do that at present with the tablets designed for swimming pools and a carbon filter to fix the taste. However water then goes to a septic tank (which won't like any chlorine) and plants which likewise could do without the chlorine. This all brings me back to looking at the local traditional way of using lime, but how much?

We do exactly the same and 'touch wood' we haven't had any problems in 5 years.The chlorine doesn't stay too long in the water as it evaporates as gas,hence the smell and the need to keep the tablets topped up.

Calcium hypochlorite (Ca(OCl)2, HTH, High Test Hypochlorite, Sentry, Perchloron, chlorinated lime, bleaching powder)

This is usually available in granular format or as non-effervescent tablets.  This is often used by military and aid agencies for large scale water treatment.  The US military uses ampoules to ease measurement of chemical needed to treat water trailers, Lyster bags, etc.  It unfortunately leaves a chalk residue that can cloud treated water and gives it a chalky taste on top of the chlorine taste.



Bleaching powder often comes in 33-37% strength and High Test Hypochlorite (HTH) comes in crystal form and has nearly 70% available chlorine.



Either a chlorination test kit is needed to titrate treatment or water can be intentionally over treated and then neutralized with a reducer.



One way to treat clear water is to first make a 1% solution of calcium hypochlorite by mixing 14 gram (one heaping tablespoon of granules) of HTH per quart (liter) of water.  Then adding 11 drops of this 1% solution can to each quart (liter) of clear water.  This produce about 5PPM chlorine, which is equivalent to 5 parts of 1% solution to 10,000 parts clear water.


5mg/L (PPM) concentrations with

Hypochlorite Granules (70% Chlorine)
Liters      Gallons      Grams
250      66      1.4
500      132      3.6
1000      264      7.1
2000      528      14.3
3000      792      21.4
5000      1320      35.7
10,000      2641      71.4


28.3 grams = 2 heaping tablespoons of granules = 1 once



Please note that HTH is highly reactive and can burn or explode if it comes in contact with reducing agents such as sodium thiosulfate, other chlorinating compounds, concentrated acids, and organic compounds such as antifreeze, oil, kerosene and gasoline.  You should never mix HTH with bleach.

Bottled drinking water at about 10c/litre is much cheaper than paying water rates in UK  ;)

Thanks for all the posts.
A couple of thoughts  ...  although bottled water for drinking is not expensive in terms of €, I would rather not use so much plastic.
And getting back to the original topic ... I take it no one has use Cal, so if and when I find out I'll post it here
Cheers

The plastic can be recycled.  Plenty of collection points around.

wrote on Aug 9^th, 2012 at 5:27pm:

wrote on Aug 9th, 2012 at 3:36pm: Thanks for the links. Interesting and the most common is the use of Chlorine in the water. I do that at present with the tablets designed for swimming pools and a carbon filter to fix the taste. However water then goes to a septic tank (which won't like any chlorine) and plants which likewise could do without the chlorine. This all brings me back to looking at the local traditional way of using lime, but how much? We do exactly the same and 'touch wood' we haven't had any problems in 5 years.The chlorine doesn't stay too long in the water as it evaporates as gas,hence the smell and the need to keep the tablets topped up.

Sorry guys, only just seen this thread. Coldalba, you seem to be worrying about the chlorine too much. It's simple to remove.


If you are using 'Activated Carbon' and not just ordinary powdered or granulated Carbon, there should not be any Chlorine left in the water at all anyway - so long as you have enough carbon and change the carbon now and then so the pores are not all blocked with contaminants.

If you are really worried about the chlorine, why not pass it though a open topped vessel with a large surface area and aerate it with a small (solar powered?) fountain? looks good and is guaranteed to remove the chlorine simply after a while simply by evaporation. this works the same way as when you fill a large bucket from a cold tap turned on full and get a strong whiff of chlorine - it's the chlorine coming out of the water you can smell.

Alternatively, pass it though a slow sand filter with an activated carbon layer incorporated. That will also do it.

Hope this helps. As a Biologist, this and sewage treatment methods, and grey water treatments, are also exactly the sort of business I'm setting up when I move over.

BTW, if you are worried about the amount of lime to use and whether it is still too high a level in the water, why not buy a 'PH meter' or some 'litmus paper', or a simple water test kit?

Please also bear in mind that putting lime into a cisterna is not the same as putting into a well where the water is continually replaced as it's used. The water in  cisternas is usually only  replaced when the levels are low. If you have too much lime in the bottom of your cisterna, then as the water level drops, the concentration of lime in the water increases. This doesn't happen with wells since the water level stays the same. Neither does it happen with chlorine since it evaporates naturally over time and so concentration drops instead of increases.



John

:-?

John

Thanks for the reply to this thread.
I use a swimming pool version of chlorine plus a carbon particle filter and monitor the ph & Cl levels so it is fine for us. As you say you can smell chlorine if there is a blast of water into a bowl, but not otherwise
My concern with chlorine is only about it reducing the effectiveness of the septic tank (where all our tap water goes). Do you think that is a reasonable concern?

I am not sure how the Cal option works  and what levels it needs to be effective. It is the traditional method in many parts of Europe and I hoped it would not have the same impact on our septic tank. Any thoughts?

Cheers

John,
Thank you for the very usefull information.
My concern is of water supplied from unknown sources,which at best will be agricultural water,or worse still from the river.(
What would you recommend to test for,such as radioactivity,before commencing treatment ?

wrote on Aug 13^th, 2012 at 9:17pm:

John, Thank you for the very usefull information. My concern is of water supplied from unknown sources,which at best will be agricultural water,or worse still from the river.( What would you recommend to test for,such as radioactivity,before commencing treatment ?

Phil,
there is no point in testing for radioactivity. There is no way to reduce it even if it's present. the chances of it being present in harmful amounts are almost nil - even from the  power station outflow on the river!

I would be more concerned with making sure the water is as clean and free from bacteria, viruses, fungi, Giardia, and  Cryptosporidium.

Let's put it this way, If I was having a well or cisterna built for drinking water (or even cleaning river water), I would be thinking along the lines of having the water pass through a slow sand filter with activated carbon layer to remove biological (algae for example) and chemical contaminants.

I would then have  a chlorination or ozone phase to kill micro-organisms, followed by  'point of use' filters to remove the killed micro-organisms.

There is plenty of good advice on the net and plenty of suitable under cupboard filters available for 'point of use' installation.

Hope this helps.
John

wrote on Aug 13^th, 2012 at 7:38pm:

John Thanks for the reply to this thread. I use a swimming pool version of chlorine plus a carbon particle filter and monitor the ph & Cl levels so it is fine for us. As you say you can smell chlorine if there is a blast of water into a bowl, but not otherwise My concern with chlorine is only about it reducing the effectiveness of the septic tank (where all our tap water goes). Do you think that is a reasonable concern? I am not sure how the Cal option works  and what levels it needs to be effective. It is the traditional method in many parts of Europe and I hoped it would not have the same impact on our septic tank. Any thoughts? Cheers

I don't think it will be too much of a problem in the septic tank, after all, the water ging into it is a small volume in relation to the tanks volume. The water in the tank will have been standing for some time and there will be plenty of time for any chlorine to evaporate and drop to very low levels. Raising the levels a bit shouldn't make much difference at all.

The lime is an option but take into account what I said earlier - AND that if there is any left in the bottom of the tank when you refill it, it will be disturbed and will  need time to settle out again before you can use the water. The time needed will be determined by various factors such as volume, depth, amount of lime present, etc. It isn't possible therefore for me to say how long will be needed. You would need to test the water before use using a test kit.

hope this helps.
John.

Forgive me for poking my nose in again.  It sounds as if you have your own on site water supply (well) ?  Would it not be simpler, cheaper and less potentially hazardous to health to simply use the water untreated for irrigation, washing and flushing and simply spend about 3 - 4 Euros a week on bottled water for drinking and cooking ?

John
Good to hear that you think the inflow of Cl is unlkiley to limit the septic tank.
I will see what I can establish about Cal and post anything back here
Cheers
and .. our water is rainfall, and we are trying to work out how best to use it (when it comes!).

I'm fascinated to find out how many people on here rely on rainwater only for their supplies.  I'm one of the lucky ones who has a well and haven't had to worry about having enough water.  I don't know if you're living here yet Coldalba or just planning ahead ?
The rainfall here is erratic to say the least.  It's not unusual to have not a drop from say April to September and then when it does come it's an almighty torrent.  The average annual rainfall is about 600mm which equates to 600 litres/sqm of catchment area.  Now I estimate that I use about 500 litres a day for everything except drinking.  I realise that may sound extravagant to some people (but we don't have a shortage).  That comes out at about 182,000 litres a year or 182 cubo's and would require over 300sqm of catchment.   That's a lot of storage space and catchment area.  Then when you've collected all of that you've got to try and keep it sweet.  If I'm talking rubbish, please let me know.  :o

Bigyin wrote on Aug 16^th, 2012 at 12:17am:

I'm fascinated to find out how many people on here rely on rainwater only for their supplies.  I'm one of the lucky ones who has a well and haven't had to worry about having enough water.  I don't know if you're living here yet Coldalba or just planning ahead ? The rainfall here is erratic to say the least.  It's not unusual to have not a drop from say April to September and then when it does come it's an almighty torrent.  The average annual rainfall is about 600mm which equates to 600 litres/sqm of catchment area.  Now I estimate that I use about 500 litres a day for everything except drinking.  I realise that may sound extravagant to some people (but we don't have a shortage).  That comes out at about 182,000 litres a year or 182 cubo's and would require over 300sqm of catchment.   That's a lot of storage space and catchment area.  Then when you've collected all of that you've got to try and keep it sweet.  If I'm talking rubbish, please let me know.  :o

This is exactly the problem with holding water in cisternas. It is not easy to keep sweet and clean. Even in small cisternas the water will go green from algae and once it's in, you can not completely eliminate it.

It is far easier therefore to have a large holding tank and feed the water in it through a cleaning system into a much smaller holding tank which is easier to keep clean because it can be used before it has a chance to go green again.

There are ways to keep even large amounts of water clean but it is not easy and it is not cheap. Chlorination is one way but it evaporates and has to be continually replaced. Lime is fine in wells but causes problems in cisternas (concentration levels, having to settle out etc.) The best way is to only clean your immediate needs completely and let the rest just filter through a slow sand filter to keep it fairly clean. please note the term 'SLOW' sand filter as opposed to any old sand filter.

If you want to see how effective sand is at cleaning water, try this:

Take a plastic 2 litre bottle. Put a small hole (1-2 mm diameter) in the lid. Cut the bottom of the bottle off. Turn the bottle upside down so the open end is at the top. Place some (a few) small clean pebbles in the bottle. cover the pebbles with small pea gravel to a depth of about 1 inch. Cover with washed fine sharp sand (washed river sand not building sand).  Take a bucket and place a shovelfull of earth in it. top it up with water and mix thoroughly. Let it stand so the big lumps settle out a bit. Slowly pour the dirty water onto the top layer of sand and let the bottle fill slowly. catch the CLEAN water coming out of the hole in the bottle lid. Amazed? I was when I first saw it. Now scale it up and you have a sand filter.

NOTE:
This is NOT a 'slow' sand filter and is still very crude at this stage. The water may look clean but it is still full of germs, chemicals, and fine sand at this stage. Do NOT drink it.  :(

John

That's all very interesting stuff John.  I obviously don't need it but I can attest to the problems caused by algae.  I pump up from my well into two cubo's in the garage connected in parallel.  The output is pumped to the taps/showers in the house.  The pipes from the pump to the taps run for about five meters along the inside of the garage wall and are the clear plastic type.  After a while, blue/green algae (I think) built up in the pipes to the extent of completely blocking one of the taps.  Happily I was able to dislodge it by moving the flexi connector about.  I flushed the system through with bleach which seems to have removed most of it and will lag the pipes later to keep the light out.
You mention sharp sand.  Do you know what the local builders merchants call it please ?

Re my last post but one.  I've just been chatting with a builder friend who gets around a bit and he tells me quite a lot of people rely on rainwater for their supply (who knew ?)  :-/ but he agrees with me that large catchment and storage are needed and most folk have to have delivered backup.

Like many, we rely on a large cisterna (35,000L) which is filled by rainwater and maybe one 15000L delivery by lorry per year for €90. The pool uses most of it. Keeping the water good is easy, just keep the light and bugs out. We use a simple 1 micron cartridge filter before using the water in the house for washing. We used a reverse osmosis filter for drinking until reading a WHO report that warned against long term use due to mineral depletion. Might try a UV filter instead but it's bottled water for drinking at present.