When it rains, it pours!

The Chartwell household/ drinking water tank of rainwater collected from the roof has a nominal capacity of 20,000 litres. Based on average estimated daily water usage of approximately 600 litres, this represent just over 30 days’ supply.

As anyone who relies on the forces of nature can confirm, you need to be water-wise-aware and you should best keep tabs on the comings and goings – the rainfall and the usage. You could, as has happened to the neighbours across the way, end up paying for a tanker-load or two of water at the rate of $360 per trip!

We keep very accurate rainfall data, so the amount of rain is simple to track – to convert these millimetres to litres is a bit of a sticky point, as there may be leaks, and also the garden tank on the other side of the house also gets a small share. We will investigate that a bit more fully after attending to the plumbing there. In total every millimetre of rain should represent 250 litres of usable water. Using my long-lost arithmetic, one would need 80mm of rain to fill an empty tank.

We also take readings of the water level in the tank using a simple calibrated home-made dipstick generally immediately after a rainfall period, and record the readings with the rainfall data. Over the past week, we’ve had gentle drizzle-showers on and off.

This morning when I saw the reading above 20,000, I said to myself, “Hello, hello, at 20,450 litres shouldn’t the tank be overflowing into the reserve tank?”

It was really a rhetorical self-quiz, because I immediately went around the back to query the matter with the overflow system manager. The overflow system manager is a grand name for an 80mm diameter PVC which runs down at a slant from the main tank to the reserve tank. It sounds a lot more posh is I call it a “system manager” and not simply a plastic pipe. The pipe is cunningly hidden from view by a forest of tall hydrangeas.

I couldn’t see the manager clearly through the dense foliage, but I listened for water running into the empty reserve vessel. Nothing at all.

Wait a mo… Over there where the pipe exits the main tank, I detect something like dripping-running water. What the…

I grab the secateurs and start pruning the offensive barricaded area. When a path is finally clear, I can see the water flowing from the outlet. But not inside the pipe via the system manager!  It was leaking at the exit hole next to the pipe!

Bad naughty system manager! We will have to schedule a disciplinary hearing for you…

 
(Above) Clearly one could see the (cleaned) path of the rivulet of water running down the outside of the main tank.

(Above) The whole setup was wobbly and moved around freely. The exit pipe was not glued to the outlet either. Someone had previously used a silicone mastic as sealant, without much success.

I drove down to Farmlands in Waikanae in search of a threaded collar and ring-nut, plus a waterproof sealant. Nope, no luck – I need to go through to Param to the plumbing centre. Tomorrow is Anzac Day, so with many shops closed,that sounds like a Saturday trip, I guess.

(Above): Back home, if I wiggle the outlet just so, I can guide the path of most of the overflow, with only a small fraction leaking past.

With cunning use of my knowledge of hydraulics and my ever-so-slightly renowned engineering skills, I have devised and fitted a Heath-Robinson-type “gasket” to the outlet pipe, which seems as if it will do the trick until Saturday. It’s actually a strip of compressed newspaper…)

Whether or Not?

While the dogs are wrestling playfully (and quite vocally) on their bed next to me, I stand looking through the window as the gentle drizzle splashes upon the panes.

Showers. Hey, its April. April showers.

Who can forget the words as sung by Al Jolson,

When April showers may come your way
They bring the flowers that bloom in May
So when it's raining have no regrets
Because it isn't raining rain you know
It's raining violets
And when you see clouds up on a hill
You know they'll bring crowds of daffodils
So just keep looking for a bluebird
And listening for his song…

It was based on the 1921 song in the Broadway musical Bombo, and subsequently they made a movie based on the 1999 Columbine High School massacre with the same title.

On a more literal note, I wonder whether or not there will be April showers in Reikorangi this month. After all, we are half-way through our Autumn (Fall) and the parched earth has started to complain about being dry and brown. On checking our rain-gauge data for April, as below, one can see that the first week was bone dry and the second has produced a paltry 22mm over 6 days

I wonder whether we will be getting the weather, or not? Accuweather forecasts:

Drizzle: 7 April

By now, you will be aware of how we regard the importance of rainfall to our existence in Reikorangi. While some parts of the country have been having regular showers, our Kapiti Coast region has been experiencing summery weather, even attaining temperatures of 30º 

As Prince William, Duchess Kate and baby Prince George alighted from their plane in Wellington yesterday, a blustery wind with drizzly weather greeted the royal party in the Caapital. At that moment at Chartwell, (60 k’s to the north if the crow flew) we had another summery day, although there was a hint of grey clouds approaching, which by nightfall was patchy but noticeable.

During the night, I heard the pitter-patter on the roof outside our upstairs bedroom. At 7:00 this morning I took the reading in the rain-gauge: 4mm – not exactly a downpour, but nevertheless nice water if you can get it. The last time we recorded precipitation was on 15 to 17 March, when 29mm fell.

Based on updated records, I have revised our rainfall data to 250 litres represented by every 1mm of rain. We therefore received 1,000 litres overnight. I am rather confused, as my previous revision indicated a number closer to 300 litres per mm.

The dip-reading at 2:00pm yesterday was 6,000+24mm = 6,000 + (24x9.0909) = 6,218

This morning’s reading is 6,000 + 110mm = 6,000 + (110x9.0909) = 7,000

A reader or two have indicated that they couldn’t really care about how much water we have in the tank, and even less about how much rain we’ve had. By way of explanation: I understand the lack of spell-binding interest, fair enough. But I use this blog as a (sort of) diary – this means that our water data will all be in one place. 

It’s a hard rain a-gonna fall…

"Oh, where have you been, my blue-eyed son?
And where have you been my darling young one?"

"I've stumbled on the side of twelve misty mountains
I've walked and I've crawled on six crooked highways
I've stepped in the middle of seven sad forests
I've been out in front of a dozen dead oceans"

"I've been ten thousand miles in the mouth of a graveyard
And it's a hard, it's a hard, it's a hard, it's a hard
It's a hard rain a-gonna fall"

The much-awaited rain came late yesterday afternoon with such excitement you’d swear we live in a desert or something.

Well, sort of excitement. Because we wanted to see how effective the cleaning of the downpipe had been, and how efficient the water harvesting process has become. This can only be determined if you have a reasonably substantial downpour.

The weather forecaster had promised that the lower half of North Island would get such a substantial shower or two late Sunday, and true to form, he was correct.

We work on the following criteria:

Main tank dimensions: D =3.00, h = 2.400
From my old maths formula:  Pi r²h = 22/7 x 1.700 x 1.700 x 2.400 = 21.79Kl

Allowing for the overflow to the secondary tank and ullage allowance, the tank therefore has a nominal capacity of 20,000 litres. A 2.4 metre length of profile beading salvaged from the shed and marked off in 220 mm graduations by Tyler produces a practical and durable dipstick… as long as it stays in one piece.

A dip of the tank at 11:00 am shows that the level lies at the 12.25Kl mark. Now bring on the rain!

The roof area is approximately 250 square metres. Therefore, assuming optimum efficiency and minimal leakage and loss, for every 1mm of rainfall, we should collect 250 litres of potable water.

This morning, we dipped the tank once more, and within the limits of practical accuracy, I am please to report that the approximately 19mm of downpour last evening caused the level in the tank to rise to 17Kl, being about 4,750 litres. Quite conveniently, 19 x 250 litres is precisely what we were expecting.

Like all good scientists, we will repeat the exercise when the next heavy rains come. In the meantime, Tyler is busy preparing the overflow tank so that we don’t waste any precious water.

Can you feel the excitement? Next time you open a council-supplied water-tap, please remember those who look towards the skies for theirs.

You know you’re in…. when

You know you’re in Reikorangi… …when the 10mm overnight rainfall in the rain-gauge outside is far more important to you than the M6.2 earthquake and numerous aftershocks felt less than 60 km away in Eketahuna.

I was always fascinated by the importance that the farming community placed on the rainfall data. Now I realise how it is elevated in importance when you’re dependent on the sky for your drinking water, your bathwater and irrigation for the plants! Yay, we can bath again – every millimetre of rain translates into hundreds of litres of fresh water in the storage tank!