rainwater-home-supply-assembly, pump, tanks etc

[Gabriël]

it is about here where my lack of knowledge should become embarrassing, note 'should' - but isn't. notwithstanding the rating my postings have 'earned' me...

it's very basic.

i have two full 10000l rainwater tanks and want to use some of it in the home. i have a pump, pressure gauge, pressure switch, pressure tank... i still need one or more non-return valves etc.

BUT, even after surfing the net, don't know exactly how to rig the system.

as the whole operation is not rocket science and presumably every farmer would know how to do it i would like your tips and tricks here - i even found suggestions of installing more pressure tanks in order to reduce the pump cycles.

regards

in Christ

gabriel

[Mark]

Hi @gabriel

Some questions before I try and give my suggestions

1. Are you connected to a municipal/mains connection?

2. If yes do you mind mixing municipal and rain (assuming you have connected the tanks to mains)?

3. OR Do you want to switch between mains to the house and tanks to the house.

4. When you say pressure tank - is this a header tank and how high above the house does it sit/stand.

Lots of questions but the various options depend on the scenario and needs (geysers - low/high pressure, etc).

Thanks

Mark

[Gabriël]

1 hour ago, Mark said:

1. Are you connected to a municipal/mains connection?

2. If yes do you mind mixing municipal and rain (assuming you have connected the tanks to mains)?

3. OR Do you want to switch between mains to the house and tanks to the house.

4. When you say pressure tank - is this a header tank and how high above the house does it sit/stand.

1 yes,

2 i do not want to mix,

3 yes,

4 it is a small 24l tank as in image, the pump, tank assembly will be waist high.

on the 1st three images you can see the assembly of the pump/pressure tank/pressure regulated switch and pressure gauge.

on the 4th image you can see where i plan to install the unit and where the water mains to the house is [actually the end, the inlet will get a valve so that when using the pump i can shut of mains supply.

the geyser is solar, thermosiphon, on the roof, 400kpa

where do the one way valve/s come?

thanks for helping mark!

[___]

I'm no expert either, but as I understand you want to avoid backflow into the municipal system (this is the law in some places/countries, don't know about here). So you usually want a one-way valve between the municipal supply and your whole setup. While the mains supply is usually at a higher pressure than your own, you cannot rely on that. If the mains is out, you don't want to accidentally feed your water (which may be contaminated, that's the main reason) into the system.

Other than that, I would just have a changeover valve (such things exist) so I can choose between one and the other. That's what I plan to do at my own place anyway, once I get to it... :-)

[___]

Come to think of it, what I would probably do is add another one-way valve on my pump/pressure tank output, so that some kind of mistakes in your valve positions don't feed municipal water backwards through your pump and into your storage tank.

[Gabriël]

good morning and thanks for all the tips and advice and good response - visible and in private messages!

from all i have learned i drew a schematic and would obviously welcome comment

[Mark]

Looks good.  The only change I would make if space is available is to move the pump as close to the tanks as possible.  That way you feed it with the correct size input pipe (eg 25mm).  You then can output any size... you don't want the pump sucking from the tanks through a pipe diameter smaller than the pump input.  

Also add shut taps to each tank so you can use both or each individually, as you may need to fill one with muncipal water in case of no rain (and water shedding).

Regards

Mark  

[SilverNodashi]

5 minutes ago, Mark said:

Looks good.  The only change I would make if space is available is to move the pump as close to the tanks as possible.  That way you feed it with the correct size input pipe (eg 25mm).  You then can output any size... you don't want the pump sucking from the tanks through a pipe diameter smaller than the pump input.  

Also add shut taps to each tank so you can use both or each individually, as you may need to fill one with muncipal water in case of no rain (and water shedding).

Regards

Mark  

Agreed. Closer to the tank is better. And I always go one size bigger on the suction side to ensure there's more than enough water for the pump not to over-work itself. 

[Energy-Jason]

This makes me happy. Everyone helping every one. 

Jay

[___]

I don't think you need a non-return valve between the tank and the pump (what does it do?). I would expect that gravity should generally push water towards the pump, and that the pressure tank already has its own valve in place.

If the pump is higher than the tank for whatever reason (eg, on my well point the pump sucks the water up), then you'd put a non-return valve there so the pump stays primed.

[Gabriël]

38 minutes ago, plonkster said:

I don't think you need a non-return valve between the tank and the pump

although the water levels are at present about 2.5m above pump the position, the pump might have to suck at stages when the level drops below pump level, and as you state to keep the pump primed, so i'll leave it there - at zar99 for the brass model it is not too much.

i've added some things in this drawing making things more practical, like a direct line from the mains to the tanks, filter...

you guys won't believe me - i searched hi and lo and couldn't find a drawing like that on the net - something which could help a dummy like me - eish...

[Don]

Hi @gabriel. Here are some pics of my setup. I tried to keep it simple. I manage my system with cut off valves only. 

To start off with, I brought the municipal water input line from the other side of the house to close proximity of the water tank. I brought in a new line and disconnected everything feeding the house in the roof. Now I have a common feed line feeding the house. By opening or closing a valves I switch between feeding from Municipal water or from the Water tank.

1.) Valve 1 Open and Valve 2 Closed - Feed from Municipal water. 

2.) Valve 1 Closed and Valve 2 Open - Feed from Water Tank. 

3.) Valve 3 gives you the option to fill the tank with Municipal water or shut it down.

4.) I drilled a hole on the side of the water tank at the top and fitted a toilet ball valve on the inlet side. That way you can keep the tank filled at all times without opening or closing valves manually. Every 3-4 months I close the inlet valve to the tank (Valve 3) and switch to Water Tank Mode. Then I run on the pump until the tank is empty and then refill it with fresh water.

 

[Gabriël]

verrrrry neat setup @Don, i note you have no pressure tank, does that have any influence on the house water pressure? how long has your pump been doing its 'thing'? is the pump noisy [i ask cause you bricked a window over there ;-)]

i just came back from agrimark with about everything i need as well as something i don't need, like 20 bags of compost - it was on a special ; but i'm sure my dearest will have good use for it.

thanks for going the xtra mile with the snaps, the lights are coming on in my head regarding this pump thing, and they are getting brighter by the moment

[Don]

Thanks @gabriel. No, I have no pressure tank. My pump pressure is set at 5 Bar, which is slightly higher than the Municipal pressure. I therefore have more pressure running off the pump than when on Municipal water. When on the pump, you need to open a tap slowly until the pump kicks in and then open it further. If you just open the tap halfway and the pump kicks in a second later, you have water all over the show and dripping from the ceiling. 

No, the pump is not noisy at all. You might hear it late at night when it is very quit trying to fall asleep and someone flushes a toilet. Yes, I had a window in our dressing room opening where the tank is standing now. You open the window and you stare at the water tank in front of the window. So I bricked up the window. 

I installed the water tank and pump about a year ago and works like a dream. Just make sure you don't have any toilets that don't seal properly. Otherwise you have a pump that stop/starts every 5 minutes. running for 5-10 seconds to pressurize the water system.  

[Gabriël]

2 minutes ago, Don said:

Just make sure you don't have any toilets that don't seal properly

i'll find out soon enough...

in the meantime i have simplified my layout, see image 'version 3'

God willing the system will be operational early next week

[___]

In my experience the pumps usually take a 1.25" (38mm) pipe on the inlet, so I would use 40mm (the old 1.5") to the tank rather than thin 25mm, especially if it's close together.

Re lack of pressure tank: My well pump has no pressure tank either, but it has the little protection unit on top. That thing has a small compartment with a diaphragm, it probably holds about a cup of water under pressure. If you have no leaks of any kind, it works perfectly. If you have leaks, then your pump will turn on every few minutes to restore the pressure.

My irrigation system has small leaks. I don't care.. it's an irrigation system after all. So I control my pump using the master valve output on the irrigation computer, I switch it off when not in use rather than relying on the diaphragm switch.

You already have the tank. It will mean the pump will switch on less often. You could probably fill a toilet cistern without it turning on.

[Gabriël]

1 hour ago, plonkster said:

You could probably fill a toilet cistern without it turning on.

yes @plonkster the pressure tank should at least manage three flushes; unfortunately i was not able to get hold of a larger tank, mine is but 20l [water capacity], i would rather go for 50l, if i can get a 50l or so i'll install it in series to minimize pump cycles etc.

my pump inlet is only 25mm [although the thread inside measures 30mm ], so i'll have to stick with that. at the moment my tank outlet is reduced to 20mm, so effectively the pump has to suck through 20mm - that reducer comes out as soon as the water pressure is low enough [water level in tank - at present full] and i can work there without being washed away.

the pump makes far less noise than my neighbours dogs, and it is right next to them. the main bedroom is on the opposite side of the house - the drawing of the house layout is totally wrong - 'artistic license' some might call it

the specs of the pump are as per image - i gather it is a bit overkill for the house, but then again all i wanted about 2 years ago was something strong enough

[Gabriël]

ok, we seem to have missed something; the pressure reducing valve [prv] as the municipal water enters the home.

on good advice the 400kpa prv i have [400kpa for solar geyser] protects the geyser as pressure fluctuations might harm it and is responsible for inter alia the shower not gushing steam when someone turns on a cold water tap.

so the pumped water has to go through the pressure regulator. i have two options, buy a second one and install it after the pump or do some piping to the default one on the other side of the house - after doing the math a new pipe seems obvious, even if it will result in a slight drop of pressure.

so herewith revision x of the scheme, sorry for the size, a pdf would have been a fraction...

[Don]

2 hours ago, gabriel said:

so the pumped water has to go through the pressure regulator. i have two options, buy a second one and install it after the pump or do some piping to the default one on the other side of the house - after doing the math a new pipe seems obvious, even if it will result in a slight drop of pressure.

@gabriel, that is why I opted to extend the Municipal feed to the vicinity of the tank and pump and have a "Common Supply Feed" to the house. All the valves are in one location. You only select where to feed from, Municipal or Tank, the rest stays the same. Otherwise you end up with multiple pipes feeding the house with multiple prv's to cater for all scenarios. When you want to switch from municipal to tank or vice versa, you have to run around the house opening and closing multiple valves.

If I run out of water 22h00 on a Saturday night after watching the rugby, had a nice braai and had a few beers, it might become a challenge to open and close all the right valves. My Rottweiler would also think I have came out to play and even confuse me more. Currently for me it is easy, close the one valve, open the other valve and start the pump. It is so simple, even my wife can do it without a manual. In your case, you would have one additional option to select from, Municipal Tank or Rain Water Tank.

[___]

I don't have a pressure reducing thingum in my present setup. There's one on the geyser and the balanced lines all feed from there, but the other cold lines are all 4kpa direct from the mains.

[Gabriël]

hi @Don, yes i see you have done your homework and are definitely prepared for that

2 hours ago, Don said:

Saturday night after watching the rugby

thing. in our case we will run the pump from the tanks for about a week per month, as we have 20kl at present i do not foresee my evening getting spoiled soon - i hope... [consumption about 250l pd for two of us]

the taste of rainwater is so superior to that of municipal that i will  for sure maintain one tank with rainwater.

regarding my wife doing the 'valve round', i'm sure i will be able to at least publish a understandable manual

i'm having a question about the bmv702, but will go to the correct section

 

[Don]

11 hours ago, gabriel said:

in our case we will run the pump from the tanks for about a week per month, as we have 20kl at present i do not foresee my evening getting spoiled soon - i hope... [consumption about 250l pd for two of us]

Try and install some sort of tank level indicator as well.

As I said before, every few months I would shut the inlet to the tank and run the pump until the tank was empty and refill it with fresh water. We were running on the pump and my wife told me we don't have any water. I estimated our daily usage and did a quick calculation - the tank level should be between 25 and 50%. I went to to pump, switched it off and on again. I could hear it pump water for a few seconds, then the pressure gauge would drop right down and the pump would stop. I did the bump test to determine how much water was in the tank. I could hear the water splashing inside the tank and estimated the level to be at 50%. The only other explanation I could think off for the pump not pumping water is that there must be a blockage on the inlet side of the pump. With these installations it is not easy to just unscrew pipes, as they are glued in with PVC cement. So I cut the inlet pipe and unscrewed it from the pump. No filter on the  inlet of the pump. Opened the valve going to the tank. Very little water coming from the tank. Unscrewed the connection to the tank and stuck my finger in there. No filter there either. Then I realized, the tank was empty. The water I heard doing the bump test was the 2 inches of water below the outlet of the tank. All that work for nothing, just because I had no level indicator.

[DeepBass9]

A simple tank level indicator is to use a float in the tank tied to some ski rope which goes through a hose pipe out the top of the tank and down the side to a weight which acts as the indicator. For the float in the tank use a 2 or 5l plastic bottle that is 90% filled with water so it has some weight and is just level with the surface. The indicator on the outside needs to have some weight as well. This obviously works in reverse so when the tank is full, the indicator is at the bottom on the outside, and when the tank is empty the indicator is at the top.

My tanks are quite far from the house so a put a CD on the level indicator so you can see it.

You can also use a pressure gauge to do the same thing, and Im sure there are digital pressure sensors you could use as well.

[Chris Hobson]

2 hours ago, DeepBass9 said:

A simple tank level indicator is to use a float in the tank tied to some ski rope which goes through a hose pipe out the top of the tank and down the side to a weight which acts as the indicator. For the float in the tank use a 2 or 5l plastic bottle that is 90% filled with water so it has some weight and is just level with the surface. The indicator on the outside needs to have some weight as well. This obviously works in reverse so when the tank is full, the indicator is at the bottom on the outside, and when the tank is empty the indicator is at the top.

A good "boer maak 'n plan" indicator..... 

One can also feel the water level in a tank. as there is usually a temperature difference and just running your hand up the side of the tank you will feel a sharp temp change. This even works on an old asbestos tank. Failing that there is always the "knock" test.

[Gabriël]

thanks guys - especially @DeepBass9, i'll try and keep it simple and the 'float indicator' should provide ample warning - although the missus is pretty accurate with the 'knock test' as mentioned by @Chris Hobson. the feel-thing is a problem as the tanks stand in the sun but i'll give it a try. another would obviously be to install a water meter and keep tabs, but that's more than a couple thousand liters of water will cost me at this stage, so i'll go with the knock and float methods for now.

have a great sunday!