Cement water storage tank in the roof?

Anne Miller wrote:I would be afraid of what all that weight would do to my roof.

Weight will be on the walls but yes it's a concern.  Unknown what weight it could bear.

First, the concrete tank would weigh a lot, even without the water weight.

Does your roof have load-bearing timbers that can handle that weight? No its rock wall I was thinking if building in water storage.

My suggestion would be to have a structure built next to the house so that the concrete tank can be set on that structure. Something like the structures they used in the day of steam engines to fill the trains.
I'll have a look at these.  It's got to be something 1 old man and a lightweight girl in a foreign language country could pull off.

Do you have people who have equipment that can lift a concrete tank?
No I was thinking it would be  built it in situ.

How would the tank get filled?
Cheap submersible pump from the well like we currently fill the 1000 litre plastic container.

I assume that you will use an electric pump capable of pumping water uphill and then up to the water tank.

Eric Hanson wrote:Jenny,

I share the same thoughts as Anne.  Concrete sounds pretty heavy up on a roof in my opinion.  Just how much water do you need to hold?  Could you possibly use barrels, either steel or plastic?  

Yes maybe that's the route to go. Slimline water storage tanks.  Or a tank that's small enough for a week if water.  

I am just thinking about how to firstly  get that much weight up on a roof and secondly how much damage that much weight would impose on a roof over time.

Our pump could handle pumping up to the roof we think.

I agree with all the advantages you already mentioned, but I would be concerned with all that weight on a roof.

I look forward to your thoughts and ideas.


Dammit, I thought I was into something here :(   :-D

Eric

Jay Angler wrote:First, I will point out that the link shows building a cylindrical tank which is a much stronger shape than a rectangle. At the very least, trying to shape your planned tank more of an "oval" than a rectangle, would improve it's longevity.

Oh yes thank you for reminding me about oo shapes being stronger.

Maybe I could put smaller plastic water barrels up there on the wall that overflow into each other. Gives me a week worth of house water.  For dishes and showering perhaps 3 x 125l plastic barrels.  I already have these barrels.

Second, know your local dangers. Are you in an earthquake zone?  Water is *really* heavy, and it "sloshes". This is why most elevated water storage tanks aren't part of the building.

There are tremors on the coast but not where we live I think.


Third, have you had an expert look at that wall? Just because it's wide enough, how sure are you that it is designed to support the extra weight. If you calculated that the 2 would hold 1000 liters that's 1000 extra kilograms of weight on top of that wall + the weight of the tanks.

No experts involved just two people on a piece of land youtubing and googling our way along.

Personally, I'd build a dedicated tower close to the house to to build a single round tank on.

John F Dean wrote:I would not put a tank of any size on my roof.  The weight of the water could be down right exciting ....add in the weight of the tank and the problem gets worse.

Tereza Okava wrote:Where I live (Brazil) most homes have large water reservoirs either up under the roof (masonry houses, right on top of a reinforced set of walls) or outside on some sort of special platform, if there is any question about the ability to bear weight. Keep in mind, no earthquakes here. I have a 500L tank in my roof, which is a good amount, but I've seen 1000L tanks as well.
Most of these tanks are made of plastic nowadays, concrete would be exceedingly heavy.
And just thinking out loud- that metal roof looks hot, my plastic reservoir sits on about 8 inches of concrete/brick, has a few feet of airspace above it, and then is covered by a row of concrete tiles, so the temperature doesn't fluctuate much. If the water gets too hot you're risking its drinkability.
If I were in your space, and had the means, I'd build some sort of independent structure next to the house (or maybe even uphill of it) but not on it. Like some sort of elevated cistern.
Do you know what neighbors have?

Tereza Okava wrote:if you search for "caixa d'água" you should find some interesting ideas, "caixa d'água laje" will show more about specifically putting it on a concrete subroof (there is some crazy stuff out there with people putting them on wooden beams, electrical poles, and other similarly nutty situation, don't look too closely at that). Most people with less structurally sound situations (wooden construction, no concrete subroof,etc) will have a 200-250L tank max.
If you're pulling from a well, there is probably no reason to have much more than this- we have 500L because we deal with frequent public water outages and rationing. Also when you choose where to put it, keep in mind you'll want to get in there and clean it every so often (worst household chore ever).

Ben Zumeta wrote:I would not put water tanks on my roof for reasons mentioned already. If at all possible, I would put them on level, stable ground as high above the house as I could. I’d regrade and/or build and foundation for it if necessary, and build large ferrocement tanks w screened light infiltration for a beneficial algae film that helps purify water (look up Geoff Lawton and Bill Mollison videos on this). My 2x12,000lt tanks that came with the house are plastic, but concrete would be preferable for the pH as you mentioned, as well as less leaching.

It may be more work and expense, but placing tanks uphill allows for gravity feed and better pressure than possible with just the roof height. You can also build the tanks taller if not under a roof, and the water pressure buildup starts at the waterline. It could also allow for water turnover with a solar powered pump (which is what we have) as any overflow could be fed through gardens, ponds, swales, animal troughs, or other biological functions that can help make your landscape more abundant, verdant, and fire resistant.

Jenny Ives wrote:The house is on the highest point of the property in the corner.

We would need planning permission and that opens a can of worms.

The house is on the highest point of the property in the corner. Rest of property slopes away

I realize now and on further reading of 'loft' water tanks that we need to have good turnover of water.  So a much smaller tank.  And as you say a way of maintaining the the tanks cleanliness.

I would not put water tanks on my roof  

 a reinforced concrete plinth that needs to be built anyway on top of the wall to lift the roof up.

In the house it's anxiety-inducing, you need to have fail-safes in case of leakage-failure-breakage-etc

Jay Angler wrote:Jenny Ives wrote:

We would need planning permission and that opens a can of worms.

I hear you, and totally understand. Going a bit smaller over-all and spreading the load into multiple smaller tanks sounds like you're willing to compromise as best you can!

And wrote:

The house is on the highest point of the property in the corner. Rest of property slopes away

Permaculture is all about working with what you've got, and compromising to do the best you can.

And wrote:

I realize now and on further reading of 'loft' water tanks that we need to have good turnover of water.  So a much smaller tank.  And as you say a way of maintaining the the tanks cleanliness.

These are sounding like excellent ideas! I've got 3 "camping" water jugs - plastic and about 40 liters each, and I agree with Tereza that they're a pain to clean - not well designed at all for cleaning. Could you design a cement tank, but with a large clean-out bung that you can easily get your hand/arm through? Some cleaning could be done through the top, but I'd want some way to scrub and flush the bottom residue, and it would have to be done in a way that the water went where you want it to go - worth putting some thinking into this part!

Ben Zumeta wrote (among several other people):

I would not put water tanks on my roof  

No - and Jenny is not doing so either. She is trying to find the safest way to put it on top of a very wide rock and masonry wall, which she's planning to reinforce, as per

 a reinforced concrete plinth that needs to be built anyway on top of the wall to lift the roof up.

I will ask if it would be possible to plan the tank location/size/shape before the concrete is poured and consider weather you could embed some threaded rod so you can put some sort of a "cage" to secure the tank that is removable for cleaning. Possibly have a two-walled system with some sort of a raised pan to hold water if there's either a leak or an overflow. As Tereza said:

In the house it's anxiety-inducing, you need to have fail-safes in case of leakage-failure-breakage-etc

Let's help think of ways to make this as safe as possible because regardless of what you make it out of, the odds that at some point it will crack seems inevitable. When I spoke to Hubby about this, he mentioned that most "concrete" is porous to a greater or lesser degree. Thus, unless the "reinforcement" as per the link you gave, is stainless steel, it will rust, which causes expansion, which eventually will likely cause a crack. Plastic when exposed to heat and time, tends to get brittle and crack (although I continue to be amazed at the blue plastic barrels we have which seem to last a very long time. Cut the top off one of them and replace it with something  removeable to make it cleanable, insulate to keep it cool, and it may be a cost-effective answer.

As Tereza and Jenny have identified, loft water tanks are a very common thing in many countries. A friend of mine has visited Panama several times, and they are very common there also. North America has plenty of risks that we live with instead of fixing (lack of decent building practices for earthquakes and hurricanes are obvious ones!) on the hope that nothing bad will happen to us. I try to find permaculture solutions which help to lower bad risks, but use what we've got available to us.

Keep researching Jenny - I have faith that you can come up with a plan which is as safe as possible, as long-lasting as possible, as cost-effective as possible, and as functional as possible. Keep posting as your plans develop!