Water tank. Divert water to mains.

If you are going to the trouble of getting a tank then I'd suggest getting that electonic diverter. Doing it manually would be a pita.

Get a good pump too. Not a cheapy. I have a 2200L tank and a Davey pump which is very good. We live on a sloping block so watering the garden with the tank water means the pump is forcing the water uphill, which a good pump will do easily.

I haven't got around to using the tank for the toilet yet. We are happy enough using it to keep the gardens watered and the cars clean.

It not only depends on the size of the tank but also the area of roof you can use as a catchment. I doubled the roof catchment area recently which means I can use the tank water more often, knowing one good downpour (we wish) will fill it again. I've estimated I have about 65 - 70sqm of catchment area so 1ml of rain gives me 65 - 70L and we get a full tank for every 30m of rain.

The pump puts out around 6L per minute so a full tank gives us about 6 hours watering. I reckon we can go for about 5 -6 weeks without any rain and keep the garden alive. I think we'd need a bigger tank, or a second one, to be able to use the water inside. I'd also think it would need some sort of filter if it was going to the washing machine. (Ours is a front loader as well - they use so much less then top loaders)

I have a neighbour with the same size tank but he tends to hoard the water rather than us it. I can't understand that thinking. If it looks like it's going to rain the the next 24 hours, i get out and water the garden so that I creat storage space in the tank. That way, the new rain water is collected, rather than having it just run out the overfolw pipe and back down the drain.

Originally Posted by journeyman Mick

Tourgy,
simplest way would be to have a "Y" valve on the outlet of your pump. Pump runs into one leg of the "Y" and a line from your mains into the other. When your tank runs low it's just a matter of switching across to your town water supply.

Mick

Thanks for the quick response blokes.
journeyman Mick, this sounds like a simple solution. I think I can see what you mean. I have never been involved in doing any handyman stuff before so I have to rely on the tradespeople that I use. I'm sure I told the plumber cleary yesterday what I wanted, but he seemed to want to go with the electronic option.

Originally Posted by Gumby

If you are going to the trouble of getting a tank then I'd suggest getting that electonic diverter. Doing it manually would be a pita.

Gumby
I woukd love to go this way but am keeping my options open for a less expensive way out. I can see what you mean about it being a pita, having to check water levels regurlarly etc but if it saves me a few bob then I am happy to go this way.

Oh, and since you mentioned that the laudry water may need to be filtered I may give it a miss diverting to there. I'll see what the plumber who eventually does the job have to say about it.

Cheers
tourgy

EDIT: what about something like this? Is this what I am after? Or is the "Y" valve otion the simplest solution?
http://www.waterstore.com.au/display_details.asp?id=1

That would be logical but I think bricks is right. That's what I've always been told by my old man. I suppose if the overflow blocked up you could end up with water from the tank in the float inlet. How it would get through the valve and into the mains, I don't know...

I read a very easy cheap and almost maintenance free system. It has the capablity of feeding your complete water requirements including hots water. I will attempt to describe in order.

From mains >backflow valve >variable pressure reducer > T junction (one coming from mains, the other side going to tank side and the middle going to house feed main feed.

From tank >pressure pump connected to float sensor >backflow valve >above mentioned T junction

Ok here is how it all works. Once connected, reduce the variable pressure reducer until the pump starts to kick in and leave at that point and thats it!

The way the system works is while there is water in the tank, the float sensor will allow the pump to fire up when any house tap is turned on. If for any reason the pump does not turn on due to lack of water or busted, all water will be drawn from the mains. While water is available in the tank and the pump is working, all water will be feed from the tank.

If your stressed about feeding drinking taps etc from tank water, install some cartidge filters on the tank side before the T junction and replace them every so often.

Why do people stress about drinking tank water? I've got nothing else to drink and it hasn't killed me yet.

I like that set up jimc, except that you are throttling the mains water pressure back to below that of the pump, so you'd better make sure it's a good pump.

Hi Tourgy,

If you want to implement a Dual Water system legally in Australia then you have to ensure that any valve that you connect to the mains supply to supply water into your rainwater tank is WaterMark approved. In addition local shires have their own requirements. Many local authorities do not allow any Dual water systems that T into their mains supply. In these locations you have to use a top up system that utilizes the Air Gap method, whereby the water is filled from the top of the tank. (Some authorities require the Air Gap to be visible from outside the tank). You cannot in this instance use any float valve with a weighted float as suggested in one of previous posts (Many float valve are not WaterMark approved). You can legally uses any of these products. http://www.anadexlabs.com.au/shop/home.php?cat=243.
No backflow prevention devices are required if you used the Air Gap method.

By the way the $120.00 2" float valve referred to in one of the previous posts is not a ordinary float valve. It is in fact a Reservoir valve that is used in large tanks and can deliver 630 liters per minute at 300kPa. So that explains the price.

Regards,
Rick

Hi Tourgy,

If you want to implement a Dual Water system legally in Australia then you have to ensure that any valve that you connect to the mains supply to supply water into your rainwater tank is WaterMark approved. In addition local shires have their own requirements. Many local authorities do not allow any Dual water systems that T into their mains supply. In these locations you have to use a top up system that utilizes the Air Gap method, whereby the water is filled from the top of the tank. (Some authorities require the Air Gap to be visible from outside the tank). You cannot in this instance use any float valve with a weighted float as suggested in one of previous posts (Many float valve are not WaterMark approved). You can legally uses any of these products. http://www.anadexlabs.com.au/shop/home.php?cat=243.
No backflow prevention devices are required if you used the Air Gap method.

By the way the $120.00 2" float valve referred to in one of the previous posts is not a ordinary float valve. It is in fact a Reservoir valve that is used in large tanks and can deliver 630 liters per minute at 300kPa. So that explains the price.

Regards,
Rick

In the process of getting a tank connected to my toilet and laundry. Hard to get hold of the plumber and wanted to know a bit about what to talk to him about.
Can someone tell me what i need to connect all this up.
Obvioulsy rainwater tank (looking at 2500lt)
A pump (what size would be adequate?)
Some sort of backflow valve
A sensor so when water low it goes over to mains.
Anything else, what sort of costs involved.
Just trying to get a rough idea of what it will cost to get all the bits!!
Cheers
McBlurter

PS: with all this water saving talk you'd think they would have a site that could explain how all this works. If you ring any plumbing supply place they all seem to want to sell you "Their" device, "all included" without explaining what it is and how it works!!!

There's this device
http://www.irrigationwarehouse.com.au/prod2265.htm
"TMC - Town Mains Water Control"
It's not showing a price at the moment - must be free!

Originally Posted by totoblue

There's this device
http://www.irrigationwarehouse.com.au/prod2265.htm
"TMC - Town Mains Water Control"
It's not showing a price at the moment - must be free!

Thanks for that. Would I actually need this or is it overkill?
I would assume all I need is some connection from the tank to the mains so water can get from tank to toilet and laundry. Would need a pump to pump the water and if no water then a system to manually turn on the mains again to those pipes.
Bricks, what is included in the "system" you talk about? I want to try and do this the simplest and cheapest way possible.
Cheers
McBlurter

Originally Posted by Mcblurter

Thanks for that. Would I actually need this or is it overkill?
I would assume all I need is some connection from the tank to the mains so water can get from tank to toilet and laundry. Would need a pump to pump the water and if no water then a system to manually turn on the mains again to those pipes.
Bricks, what is included in the "system" you talk about? I want to try and do this the simplest and cheapest way possible.

The simplest and cheapest is not to have any mains backup. If the tank runs out and you can't flush the toilet, just put some water in the tank with the hose.

If you have ever seen what comes out of a tank sometimes, you would not want it to contaminate your mains. That's what one-way valves and air-gaps are for. Since you want the cheapest and simplest way, I guess you're going to just have a leaf filter on top of the tank (like me) and that means your tank water is at times not going to be pristine. I've got a 19mm irrigation water filter to protect my pump from chunks but we only use tank water on the garden. Sometimes the water comes out brown like tea, plus other times you get rust out of the pump (unless you get an expensive stainless pump).

Another thing about mains backup: if it tops up the tank automatically, it's my guess that the water in the tank is then subject to water restrictions (e.g. in Melbourne you can't water your garden 99% of the time). I haven't ever seen the details of the water restrictions in legalese but they must be somewhere, or people couldn't be penalized for breaking them.

If you have a pump-based backup like the Davey Rain-bank then I presume you could water the garden after you turned off the mains-supply line to the Rain-bank.

Originally Posted by totoblue

Another thing about mains backup: if it tops up the tank automatically, it's my guess that the water in the tank is then subject to water restrictions (e.g. in Melbourne you can't water your garden 99% of the time). I haven't ever seen the details of the water restrictions in legalese but they must be somewhere, or people couldn't be penalized for breaking them.

You're right. A few month back according to the local rag someone had their water supply restricted until their tank set up was disconnected from the mains and fined accordingly for breaches of the restrictions.


Peter.

I've wondered about this too.

It seems to me that we are trying to make a simple task complicated. I'm thinking 'forget automatic switchover' Why not just put some sort of control on the tank, so that the pump won't run if the level is too low. I'm happy to switch the valves over, but I'd rather not fry the pump when we run out of tank water.

woodbe

Originally Posted by woodbe

It seems to me that we are trying to make a simple task complicated. I'm thinking 'forget automatic switchover'

You could get the plumber to put one of those flexible stainless hoses near the tank so you can disconnect the toilet from the pump and reconnect to a mains tap nearby. That would be cheap, satisfy water restrictions and no problem with contaminating the mains. Only downside is that it is manual.

You could also have a separate small tank that had mains backup, was fed from the pump, and was located high enough to have gravity flow to the toilet cistern. That way you could still pump your main tank's water onto the garden, and wouldn't need two pumps.

BTW my pump (used only on the garden) doesn't have a pressure switch. It is one of those QB60 pumps you can buy on Ebay - I paid about $60 delivered. It is plumbed with irrigation pipes and turned on and off with a wireless remote switch from Bunnings. I was a bit dubious about the range before buying it, but it works very well and it doesn't seem to be phased by walls, windows, roofs, ground etc between the remote and the switch. I was cleaning out a small length of roof gutter recently (with tank water - there was a bit of gunk in the gutter from some work I was doing) and I was up a ladder with the hose and the remote and it worked fine despite there being roof, guttering, wiring, window, steel patio railing, concrete patio etc between the transmitter and the receiver. The remote has batteries obviously (note Bunnings don't sell batteries to suit!) but the switch is powered by the mains that it switches. IIRC the remote and switch was $50-odd plus a couple of dollars for an extension cord to connect to the switch.

I got a quote from a company who sell tanks but also connect tanks up to toilet etc. Am looking at a 2400lt waterwall tank. Will need to connect two downpipes to it, one right where tank will be, other from about 6mt away. I asked for a quote on manual and auto and wanted a detailed itemized account, which they didn't do. Quote has come in for the princely sum of $5800 (inc GST)
Tank is 1250, rainsaver with pump is about 1500. Has a list of other stuff, but for labour they are charging $2900 . Geez for this amount might as well put in solar hot water or something that will actually recoup my money, rather than just a feel good, save water, save the planet thing. Looks like everyone is cashing in on the $500 rebate. Will see what my elderly step father (he's nearly 80 and still plumbing!!) can come up with!!
Cheers
McBlurter

A manual change over would be the easiest, when the water runs out, turn off one valve and turn the other on. On the mains side (this is in Syd. water area) you only need a DUAL check valve to protect the mains, which is different again to a DOUBLE check valve.

Originally Posted by wonderplumb

A manual change over would be the easiest, when the water runs out, turn off one valve and turn the other on.

I couldn't agree more. My system has a duo valve to provide both backflow prevention and mains isolation near the front door, and a ball valve that joins two taps together (one plumbed normally, the other directly to the pump). The two valves are placed about 10 paces apart - for maximum economy of installation - and I throw them manually when the tank level requires. I have previously described the system in greater detail in this thread [ http://www.woodworkforums.ubeaut.com...t=42806&page=3 ]

In practice, I only have to turn a couple of taps three of four times a year at most! Don't get me wrong, I love electrical and automatic (that is my trade after all), but why would you bother? Weigh up the maintenance, repairs, running, and additional capital costs against the effort of throwing a valve... No competition IMHO. If you buy the right pump (ie. one with built in 'run dry' protection) there is no downside even if you do forget to throw the valves. You just get reminded when the taps stop working

Pcal

Originally Posted by munruben

He is not using a flow back valve and because his water meter is some 30 meters from his house he reckons he would not get a flow back contamination with the mains water.

Hi mate I dont want to sound like a 'know it all' or a 'do gooder' but it is essential that a backflow prevention device is installed to protect the authority's main from cross contamination. Your mates house could be a kilometre away from the meter but if you get a negative pressure in the line due to the authority doing routine maintainence or a main bursts you will find that the tank water will drain out back into the main, given the right circumstances. Any water pipe that is above the main (and 99% of them are) will drain back to the low spot. If the local water authority found this out your mate would be crucified!! I understand that in Brissy they are having a big drive to replace existing water meters with new ones that have a "DUAL" check valve integral with the meter to stop this kind of thing. The authority dont care if you poison your family or workers in a factory environment but will do anything to protect their water mains from contaminants. But then again tank water would HAVE to be better than the tap water in Brissy!!!!!!!!!!!!!!!!!!!!!!!!