HDPE
High Density Poly Ethylene pipe is wonderful. The closest thing to no leakage yet. The rest of the world has us behind in this product. My first exposure to HDPE was at Loch Lomond because that is what they do with decoder control, no ugly field controllers. David Brench and his team do not know how far ahead they were with this system, little did I know how much trouble we were about to cause.
The largest problem we have in the USA is the acceptance by the installers. The installation procedures on new construction by today's "top builders" and compressed schedules do not allow for this type of piping to be installed quickly and when the pipe is damaged by the next contractor on site it is difficult to repair properly. PVC is much easier to work with but not always the best choice for the entire project.
The recent events in the gulf has caused HDPE prices and availability to skyrocket. There are places and opportunities on every project to use HDPE. be careful with the sizing as the Outside Diameter is the same for all pressure ratings. The higher the pressure rating (at 72.3 degrees) the thicker the wall and the larger the restriction. It is not unusual to oversize the project by one size for the increased pressure ratings needed. If the pipe is exposed to the sun it will change lengths and may not fit in the trench with turns or tees.