Category: Rainwater harvesting

Last year there was a drought, I was short of water and had to transport 35 gals a day from Atlanta to Pickens to maintain key plants.  I then resolved to increase my 6,000 gal storage capacity and in May I installed a 2,100 gal tank in a separate location and filled it from my other tanks.  More rain quickly refilled the depleted tanks.

I irrigate my vegetables and fruit trees plentifully and they are producing a bumper crop of squash, cucumbers, apples, pears and also tomatoes, okra etc.   However with minimal rain past 3/4 weeks my big tanks are almost dry so I must tap into the new storage tank, which is separate from the other tanks.  I could pump directly to the crops or refill the main storage tanks.  To refill I could run a line directly to the tanks or tap into an existing feeder line.  I decided to tap into a nearby 4″ line which runs from the house gutters to two two 1,400 gal tanks.  I scrounged around and found enough fittings and surplus 1″ pipe to do the job.

I uneventfully pumped 1,000 gals.  The rain forecast for today and tomorrow is no longer forecast, so time to irrigate.

Btw – our Giant Korean pear tree is now producing and its pears are pest free and large and juicy.  They could be sweeter but this is the beginning of the season and our early picks have not fully matured. 

I have storage capacity for about 6,000 gals of rainwater.  Last November the drought was so bad I was transporting 35 gals of water from Atlanta to my farm each visit – see “making do” post dated Nov 15, 2016.  Additional water storage was needed.  I have a 2,500 gal tank and would like to have ordered another (cost $860 ) but was told shipping cost would be very high.  It was recommended I order the 2,100 gal tank for $920 (yes the smaller one costs more) and the freight would be $220.  So I placed the order before my Pacifica trip and yesterday it arrived.  See pic above.

The tank is 90″ high and 87″ wide and weighs 290 lbs.  Of course there was drama with its delivery.  I stressed, when I placed the order that the one lane bridge off the highway when approaching from the east, could not take a big trailer.  They said the driver would call well before he reached the house and I could then instruct him on which road to use.  He called me after he had reached the one lane bridge, was exasperated, and had to back his humongous trailer all the way up the hill and then approach from the west.  The tank was at the end of the trailer closest to the cab and we 2 battled to hoist the tank over some other orders, but we succeeded, slid it onto the road and he and I rolled it up the driveway to its overnight resting spot which you see in the pic above.

Prior to its delivery I had much deliberated where to place it and decided it should go on a ledge below higher ground.  With my bobcat I had pulled out the small pine trees and removed the topsoil and then with shovel and pick I leveled the 8ft by 8ft  staging area and dug a half circle drainage trench on the high side to prevent water eroding its base.    I laid plastic sheeting on the staging area also to prevent water eroding its base and this morning my neighbor helped me roll and place the tank in position.

I stopped at Tractor Supply this morning to buy a 2″ valve which you can see at the bottom of the tank.  The 1″ pipe at the top is moving water from my other tanks to this new storage area.  It is expected to rain tomorrow and I want to relocate at least 1,500 gals today so my other tanks can accept the rain.

My neighbor who is a house builder has surplus lumber and metal roofing and I will contract with him to help me build a roof above this tank to which I will add a gutter and so capture any rainwater which lands on this area as well. 

So I hope this all works out well and, from transporting 35 gals a day during the dry season I now hope to have an additional 2,100 gals of storage.

I received some comments on my rainwater harvesting and gravity feed irrigation system.  Luke from Australia is surprised at the amount I collect.  There are simple formula on the internet where you multiply annual, or monthly or daily rainfall in inches or cm by the area of the roof and can easily derive in gals or liters the amount collectible.  And the volume is often bigger than you would expect.

Because of our continuing drought in N. Georgia I am going to expand my storage system from about 6,000 gals to about 10,000 gals so I can retain more of the rain that falls and not lose so much from tank overflow in the rainy months.  The rain that does not fall on my roofs I try infiltrate into the soil with contour ditches thus minimizing or eliminating  ground runoff altogether and soil erosion, and the soil to some degree acts as my storage tank.

Benjamin from Florida mentions that Geoff Lawton says algae in the irrigation storage tank are beneficial.  I seem to remember Geoff saying this in his pdc.  I think life in irrigation water is good and I make and use compost teas throughout the growing season.  Problem with algae is it clogs the bubblers I use for watering my orchard, but is not a problem when I use a hose.   I find algae comes out mostly at the beginning of the irrigation cycle, because it has settled near the outlet, or when you use the last remnants of tank water and the outlet is pulling horizontally what has settled at the bottom.  The quick flush I do at the manifold to eliminate air pockets also clears a lot of the starting algae  http://www.nutrac.info/2016/05/20/additional-thoughts-on-airlocks/.

Water comes down the hill in 1.25″ pipe and if the pipe is empty I flush out the air through the white ball valve.  The water jets out and the stone is to slow it down and direct it in a channel to an apple tree.  Plastic ball valves are best – they are cheaper than bronze, less likely to crack from icing and shut off water better than gate valves.   There are 3 valve controlled lines to the orchard and one to the vegetable growing area.

With the water flowing to the orchard I unscrew the furthest bubbler in the line because by removing it for inspection and cleaning, it allows water to flow down the line removing air bubbles and collecting and ejecting any debris along the way.

Then I visually inspect each bubbler to check that water is flowing and unscrew and clean those which are clogged.

For the vegetable area I split the incoming line into 2 each with its own valve and hose.

My rainwater harvesting system (elsewhere described) includes a 2,500 gal storage tank which takes water from the carport roof.  Rain has been sparse but on Saturday we had a short heavy deluge and I noticed that both gutters which feed the tank were overflowing.  I was surprised since a month previously I had connected a hose to the gutters and each had drained into the storage tank.

The drawback with testing for a blockage with a hose is if a pipe is partly blocked the water will still flow and seem ok but that slower flow cannot accommodate a heavy downpour.   The reason for my recurring pipe blockages is poor design and so even if the pipes are clear, the gusts which precede a storm can dump leaves on the roof which will clog a weak system.

As you can see below I capture water in a 4″elbow positioned below the gutter downspout and then reduce the flow to a 2″ pipe which runs to the storage tank.

The old design had the two 2″ pipes connecting to expansion joints connected to a 4″ T connection which fed into the top of the storage tank.

I cannot recall why I used such a convoluted design.  Perhaps I had surplus 2″ pipe though the cost of the expansion  joints should have been offputting.  Perhaps the thought of using heavy thick wall 4″ pipe was a deterrent.  Today I resolved to fix the problem and as I considered my options I decided to keep it as simple as possible.  Why not use thin wall 4″ pipe and run it from the downspout directly to the storage tank.  This would eliminate the need for 45 degree connectors and a T joint and direct the water to the shortest route with a continuous down slope to the tank instead of a horizontal run to the T connection and then the down slope to the tank.  Keep it simple stupid!

So here is the new connection in place of the connection first shown.

And below is the connection of the 4″ pipes to the storage tank – a straight run with a 90 deg elbow at the end to dump the contents into the mesh filter at the top of the tank.  Since the pipes can be raised vertically it should be easy to remove and clear the mesh basket, when needed.

This is the design I should have used at the outset, the cost of the new design is less than the old design and I am hoping for no future blockages.  And why didn’t I think of this at the outset.  I wanted the weight of the water and the pipes on the wall rather than the rafters and aesthetically it looked less intrusive, plus I didn’t have the experience of recurring blockages and knowing how to keep things simple.

I harvest rainwater and when I need to irrigate I pump the water to a tank at the top of a hill (right hand tank in the picture) and use gravity to move the water from the tank to its final destination.  See my description of the system and airlocks at airlock problems

I use a 1.25″ pipe to take the water from the top of the hill to the base of the hill and then I use a manifold to direct the water into four 1″ pipes, three of which irrigate the orchard with positioned bubblers and the fourth goes to the vegetable growing area where I hand water with a hose.

Over the years as my patience with air bubble delays diminished, my progress towards a solution increased.

a)  In the beginning I opened the valve to the hose at C and waited for the trickle of water to slowly increase in volume as some but not all of the air bubbles were expelled by the water pressure.

b)  Then I made a tee at C with 2 water valves, one to the hose and the other to a short length of pipe.  I would open first the valve to the short length of pipe and the water would flow more quickly since it did not have to go through the hose.  With the water flowing faster, the blockages cleared quicker.  It sounded like a train gradually gaining speed.

c)  I discovered that if I opened and then quickly closed the valve to the short pipe it increased turbulence in the downhill pipe since the water coming down backed up, and then if I quickly opened the valve again the water appeared to come through with more pressure and bring more air bubbles with it.

d)  But this all took time so I developed a smarter approach.  Before starting with C, I went to the manifold at B and opened a spare valve.  Now the water rushed out with quick stabbing pauses as the air in the 1.25″ pipe was ejected.  It took very little time to clear all the air in the pipe from A to B because this pipe was at a steeper incline and larger diameter than the pipe B to C.  Then clearing the 1″ pipe from B to C was much quicker.

e)  And finally, to avoid air blockages all together I made my final change.  I had gate valves at the manifold and some trickled water in the fully closed position so overnight the pipe from A to B lost water.  I replaced the gate valves with ball valves and eliminated all leaks so the full length from A to B and B to C was full of water with no air pockets before I began irrigating.  The trick was to stop watering before the tank at the top of the hill emptied.

These procedures have minimized the inconvenience of air pockets in my gravity fed irrigation setup.