LDPE Pipe versus hoses for garden irrigation?

Question

I am wondering if mounting a hose on the house wall is much worse than using LDPE pipes which seem to be the standard for irrigation.

I found that working with hose is much easier because it can bend much better than LDPE pipes, saving me from losts of L and T sections which are yet another possible source of leaks.

Note: I am referring to use of 16mm pipe/hose for distances like 5-20m around the house.

For the moment I see only downsides from pipes because, if hit, they will crearly break. Also LDPE seems to be rated only for 4 bars, and my water pressure goes close to 5 bars. Even the cheapest hoses do work with more than 10 bars.

Answer 1

If I understand your question correctly, it all comes down to pressure loss, flow, and distance. I'm not familiar with LDPE specifically, but have used PE. While the specific numbers might very a little between LDPE an PE the concept would stay the same. I'm also from the US, but will take a stab at the metric.

If you're using 15 mm PE the suggested max rate of flow is 0,252 l/s. Over 100 m there's 1,435 bar loss. If you're using 20 mm pipe, the max flow is 0,568 l/s with a loss of 1,320 bar per 100 m. The suggest max velocity is 1,5 m/s, and is what drives the max l/s.

For those in the US that a 1/2" PE pipe with a max flow of 4 gpm. Over 100 ft there's 6.35 psi loss. If you're using 3/4" pipe, the max flow is 8 gpm with a loss of 5.84 psi per 100 ft. The suggested max velocity is 5 ft/s.

I don't have the numbers in metric for a typical water hose, but I think you can extrapolate. If not, I can do the calculations at a later time. To make everything the same, I'm assuming a max velocity of 5 ft/s. For a 1/2" hose (which I don't see very often), the max flow 3.1 gpm. Over 100 ft there's a 10.77 psi loss. I think a 5/8" hose is more common. For those, there's a max flow of 4.8 gpm, and a 9.36 psi loss over 100 ft. For a 3/4" hose (also very common here) you have a max flow of 7 gpm, and a loss 7.18 psi per 100 ft.

The basic take away is that PE (and very likely LDPE) has less pressure loss, and higher flows rates over the same distance than a typical garden hose. This may not be an issue for you, depending on how much water you need, and how much pressure loss you're willing to have.

The other thing to think about is perhaps LDPE isn't the correct material. I saw there was also a HDPE, but again I don't know anything about it. The PE I've used in the US comes in at least 2 thicknesses and seems to handle our typical city water pressure.

PVC (typically used in the US for in ground irrigation) comes is a variety of thickness, and sizes. Most of it isn't UV resistance, but the thicker sizes are actually remarkable strong (Sch 40 is what I typically use for all my irrigation). It'll hold up to some good wacks with a shovel when buried. The trade off for thicker walled pipe is increased pressure loss. It's probably too rigid for your application, but I wanted to throw that out also.

Answer 2

If I understand your question; it is whether automatic irrigation through 1" pvc pipe divided into zones and includes a backflow device on your water supply or manual garden hose and sprinklers?

In ground irrigation pipe does not break often. You have to 'blow out' the system before winter every year and have your system re primed and inspected every spring, usually included when you hire someone to 'winterize' your system. I am very familiar with in ground irrigation. What breaks are the heads, even the popups, not the pipes in the ground.

But for my own personal gardens/lawns I go the other route; garden hose and my absolute favorite are the cheapest oscillating sprinklers you can find. Under $10 bucks a fixture, I always have a few on hand. Never use the expensive brass or any expensive oscillating sprinklers. They end up so wimpy! The cheap ones out do the expensive in pressure and delivery.

Oscillating (think fan sprinkler) is far better for soil absorption and especially important on sloped property. They put out much more water, cover larger 'zones' that can be increased by sitting the sprinkler on a saw horse or whatever, deeply watering faster with no run off.

Automatic irrigation systems remove the owner from the watering process. I teach how to figure out the amount of water delivered within a set amount of time at whatever the water pressure allowed in the system. I use kitty cat food cans. Spread them all over the zone, turn on the zone for 15 minutes (for example) and the amount of water in the cans tells me how much water during a set time (hopefully automatic systems separate plant beds and lawn) all the info I need to set the timers. The gold number is 1 inch per week. Dividing this amount into the fewest possible deliveries is the goal. Once per week for both lawns and ornamentals (vegey gardens are different) is ideal once those plants have been trained for deep roots. (read answers on lawn care, please, on this site).

Using manual irrigation is the best way to be involved with your garden and does the best job for your plants and your water bill. Test it the same way using straight sided cans; how much water is delivered within a set amount of time.

I like when we just forget to turn it off and that ground gets soaked! Then you do not water again until you see 'footprints' on your lawn or your plant beds are dry a good inch to 4" below the surface. Depends on the type of plants. Another reason to group like need plants in the landscape.

This is how you train your roots to be drought tolerant as the roots grow deeper and wider to be able to use moisture 4 to 6 inches below the surface. This saves on your water bill and protects plants from stress or going into dormancy. I sure hope I read your question correctly and this answers what you need. If not, please let us know! How large is the area you want to irrigate? What are the differing plant needs? What type of soil do you have? In what zone do you live? Are we talking cool season lawns? Warm season? Plant beds?