Someone who had a lot of experience with river pumps might work this out quicker than me. Or maybe I am a slow learner.....

This summer feels like it has been very dry. We have had a couple of dumps of rain, and in fact have had more than average summer rain. But because its been so hot, and the rain is every couple of weeks, things are drying out. My paddocks were green and lush a few weeks ago, now everything is yellow and dessicated.

But this year my vegie garden is doing well, for two reasons. One, I renovated some of the garden beds. I dug them out to a depth of half a metre, filled the bottom with re-used hydroponic mulch which i got from a tomato farmer, then a layer of really good soil from the composting we have been doing. I rebuilt the garden beds to raise them. The vegetables that are growing in them are big-leaved and lush looking. And I have been watering them, every couple of days they get a good soaking. The underlying hydroponic matting soaks it all up and the plants tap into it for days.

The water is coming from the river pump. Like most people on a river in Victoria, we have a basic water license, Stock and Domestic. We can draw water for those purposes, as long as we don't do anything silly like, say, run a market garden or irrigate a commercial orchard. We don't. In fact we've been audited, and the chap from the water authority took one look at our pump and said, "That's all I need to see. You can't possibly use too much water with that pump." (They can also look at aerial maps. Its pretty obvious from above who is irrigating.)

But as summer progresses, the process of pulling water from the river gets more complicated. Most of it relates to the river height dropping. The inlet should be, ideally, in a depth or more than a metre. That's not easily found where we are. I make do with a depth of about 80 cm, and I expect it adds to the strain of the pump pulling the water uphill. But the other issue is that as the river slows down, it start to drop more sediment.

This time last year my pump filled with sediment and sand, and in the end I had to disconnect it and take it into town for repairs. Busy time of year, hard to get parts, it took time and by the time I got it back the vegie garden was burnt out.

So, this time I added an extra filter to the inlet. Its a 2 metre piece of agricultural pipe, screwed onto the one-way check valve, with a lot of tiny holes drilled into it. (The check valve allows water to be pulled into the pipeline, but is spring-loaded and closes once the pump is turned off, so all the water in the pipe doesn't drain out.) Now, before the water enters the check valve, it is pulled through the 2 metre pipe. The pipe end is sealed. Water can only get in through the small holes. It won't stop grains of sand, but it sieves out sticks and basic organic sludge that accumulates on the bottom of a slow-running river. (Theoretically I could take the pipe further out to where the river runs faster, and there is less sludge accumulated, but the long plastic pipe becomes more at risk of being bent and damaged by the stronger current.)

But, over time the holes slowly become filled or blocked. The evidence of that was that the pump started to lose pressure as less and less holes remained viable. So into the river I go, pull the pipe out and clean it. Oddly, though there wasn't really a lot of obstruction in the pinholes. It ran for a day, then started losing pressure again. I stewed over it overnight.

The pipe from the pump to the house is 2". The pipe from the river to the pump is 1 1/2". Maybe the pump is trying to send more water than it receives, especially with my potentially throttling pinhole pipe in play.

One of my hard-learned lessons here is that it is good to have as many gate-valves in a system as possible. It really helps with sectioning problem areas and quarantining problems. My river pump has a gate valve directly on its exit. So, rather than fully open the 2" pipe to water being pumped uphill, I only opened it partially. It means less water arrives at the end, but that's ok, it just means I water each segment for a longer time period. With less water. At the top end the tap watering the vegetables was cracked open, but just enough.

So, once I started this a new issue emerged. The pump would run fine for a few minutes, then simply cut out. It's probably obvious, the issue was caused by me over-correcting. It took me another sleepless night to work it out.

By throttling the flow I was, of course, reducing the amount of water arriving at the top. So the pump, which has some built in smarts, was shutting itself off whenever it was delivering "enough" water.

Today I started again.....open two taps fully at the top end, opened the gate-valve on the pump fully, and it all worked fine. I expect in a week or so it will start the losing pressure routine again, which means I have to clean the inlet again.

Unscrewing the 2 metre perforated pipe is easy enough, but putting it back on is frustrating. Over time unrestricted lengths of pipe tend to curl, and trying to screw on a 2 metre length of curved pipe in the flow of a river is difficult. What it needs is, say, a set of shorter lengths of pipe, and a camlock (clip-on/firehose-type) connection.

I'm thinking about it....!