12 mm vs 16 mm Drip Lateral: Which Diameter Should You Specify?

What the diameter actually changes

Both of our flat inline laterals are manufactured to IS 13488:2008 in Class 2, both deliver 4 litres per hour from factory-fixed emitters, and both work at 1.0 to 2.0 bar. The diameter is not a quality difference, it is a capacity difference.

A wider bore carries more water for the same pressure loss. That is the whole story: 16 mm holds its discharge over a longer run and tolerates a steeper field, while 12 mm loses pressure sooner along the row. If your laterals are short and your ground is level, that extra capacity buys you nothing.

When 12 mm is the right answer

Choose 12 mm for closely spaced row crops on short runs and reasonably level ground. The narrower bore is lighter and more flexible, so it is easier to handle, and it costs less per roll — a block that does not need the extra capacity should not pay for it.

It is also the friendlier lateral to move. The flat profile lies close to the soil, which cuts wind drag, and the lighter wall makes it easier to lift, re-lay or keep for a second season.

When to move up to 16 mm

Step up to 16 mm when the lateral run is long, when the field slopes, or when the sub-main already runs at the upper end of the working range. The wider bore tolerates higher pressure and keeps the far end of the row close to the near end — which is what stops a block being well watered at one end and barely at the other.

It is also the better choice where a block has to be run as one long lateral rather than split into sub-blocks, because splitting means more sub-main, more fittings and more labour at installation.

The spacing difference that comes with it

The 16 mm lateral is the finest-spacing option we manufacture, with emitters fixed at 30 cm rather than 40 cm. That puts roughly 33,000 outlets into a single 5000 m roll.

Denser outlets mean a smaller, more frequent dose at each plant and a more even moisture band through the root zone, which is what high-value horticulture responds to. Wider spacing suits crops with larger root volumes, where one outlet can serve more soil.

Specifications at a glance

Common questions

Can I run 12 mm and 16 mm laterals on the same block?

You can, but it is better not to. The two bores lose pressure at different rates, so a mixed block tends to over-water the 12 mm rows and under-water the 16 mm ones. Keep one diameter per sub-block and valve it separately.

Does 16 mm deliver more water per emitter?

No. Both are rated at 4 litres per hour. The 16 mm lateral carries more water in total because it can supply more emitters over a longer run, not because each emitter discharges more.

How long can a lateral run be?

It depends on inlet pressure, ground slope and how many emitters are downstream, so it has to be worked out per block rather than quoted as one figure. If the far end of a row is visibly weaker than the near end, the run is too long for that diameter or the pressure is too low.