General HDPE Pipe FAQ

Q1: Is HDPE pipe safe for drinking water?

Yes. HDPE pipes made for drinking water use special approved materials. They meet strict safety standards (like NSF certification) to ensure they don’t add harmful substances to the water.

Q2: Does HDPE pipe come in both iron pipe size (IPS) and ductile iron pipe size (DIPS) outside diameters?

Yes. HDPE pipe is available in two main sizing types:

• IPS (Iron Pipe Size) — matches the outside diameter of black iron or carbon steel pipe. Sizes usually range from ¾ inch to 65 inches.
• DIPS (Ductile Iron Pipe Size, sometimes called CIPS) — matches the outside diameter of cast or ductile iron pipe. Sizes usually range from 4 inches to 36 inches.

Q3: Is small-diameter HDPE pipe and tubing available in iron pipe size (inside diameter controlled) and copper tube size?

Yes. Small HDPE pipes come in two styles:

• SIDR (Standard Inside Diameter Ratio, inside diameter controlled) — typical sizes from ½ inch to 3 inches.
• CTS (Copper Tube Size, outside diameter controlled, often SDR) — typical sizes from ¾ inch to 2 inches.

Q4: Where can I find dimensions like outside diameter, wall thickness, and inside diameter for different HDPE pipe sizes?

You can find this information in:

• The HDPE pipe manufacturer’s own published guides or catalogs.
• Official ASTM standards for HDPE pipe.
• The Appendix in Chapter 6 of the Plastics Pipe Institute (PPI) Handbook of Polyethylene Pipe (2nd edition).

Q5: What does HDPE stand for?

HDPE stands for High Density Polyethylene.

Q6: How does using HDPE pipe save money for water utilities?

HDPE pipe offers the lowest long-term (life cycle) cost compared to other options. It saves money through:

• Almost no leaks (or very few), so more water is billed and less is wasted.
• Better water conservation.
• Less need for new treatment plants.
• Fewer repairs and maintenance teams.
• Fewer breaks in cold weather.
• No drop in water flow over time (unlike pipes that corrode or build up inside).

Q7: Is HDPE pipe an environmentally friendly (“green”) choice for piping?

Yes. HDPE is safe during making, use, and even if burned. It helps save water (no leaks at fused joints) and uses less energy overall.

Q8: What do DR and SDR mean?

• DR (Dimension Ratio) = average outside diameter divided by minimum wall thickness. (It’s also used for other pipes like PVC.)
• SDR (Standard Dimension Ratio) is a specific type of DR from a standard list of numbers (like 9, 11, 13.5, 17, 21, 26, 32.5). These allow manufacturers to make pipes with consistent, preferred ratios. All SDRs are DRs, but not all DRs are SDRs.

Q9: Why is a fusion joint better than a gasket joint?

A fusion joint creates one continuous pipe with no real “joints” — it’s like a single piece. This makes it much better at preventing leaks. Gasket joints (used in many other pipes) can leak if: the gasket is installed wrong, dirt gets on it, it’s not lubricated properly, there’s vacuum pressure, ground shifts, temperature changes a lot, or surges blow it out. Fusion joints avoid these problems and are far more reliable for stopping leaks.

Q10: Does trenchless installation save money compared to traditional open-cut trenching?

Yes, more utilities are choosing trenchless methods because they often save money overall. Benefits include:

• Faster work and installation.
• Quicker permits and design.
• Less disruption to roads, businesses, homes, parks, and trees.
• Less damage to roads (and lower repair costs afterward).

These changes make trenchless a smart, cost-effective choice in many cases.

 

 

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