For drinking water, the best type of pipe depends on several factors such as safety, durability, and installation requirements. Here are the most common types of baby water pipes used for potable water systems:

1. Copper Pipes
Advantages: Copper pipes have been a standard for decades due to their durability, corrosion resistance, and natural antimicrobial properties.
Safety: Safe for drinking water and doesn't leach harmful chemicals.
Lifespan: Long-lasting (50+ years).
Cost: More expensive than other types of pipes.

2. PEX (Cross-linked Polyethylene) Pipes
Advantages: Flexible, resistant to scaling and chlorine, doesn't corrode or develop pinholes, and is cheaper and easier to install than copper.
Safety: Safe for drinking water; approved by most health authorities.
Lifespan: Long-lasting (25-50 years).
Cost: Generally more affordable than copper.

3. CPVC (Chlorinated Polyvinyl Chloride) Pipes
Advantages: Resistant to corrosion and high temperatures, commonly used in residential plumbing.
Safety: Safe for drinking water but some concerns exist about leaching chemicals over time, particularly in high-heat situations.
Lifespan: Long-lasting (50+ years).
Cost: Relatively inexpensive and easy to install.

4. Stainless Steel Pipes
Advantages: Extremely durable, corrosion-resistant, and doesn't affect water taste.
Safety: Safe for drinking water; doesn’t leach harmful chemicals.
Lifespan: Long-lasting (50+ years).
Cost: High cost but offers superior durability.

5. Galvanized Steel Pipes (not recommended)
Disadvantages: Galvanized pipes are outdated and can corrode over time, potentially leaching lead and other harmful substances into the water.
Lifespan: Shorter than other materials (about 20-50 years, but prone to issues sooner).

6. PVC (Polyvinyl Chloride) Pipes (not for hot water)
Advantages: Lightweight, easy to install, and inexpensive.
Safety: Safe for cold drinking water, but not recommended for hot water because it can release harmful chemicals at high temperatures.
Lifespan: Long-lasting (50+ years).
Cost: Very affordable.

Recommendations:
Copper and PEX pipes are generally the best choices for drinking water in terms of safety and durability.
Stainless steel is an excellent but more expensive option.
CPVC is a decent alternative, but PEX is usually preferred for ease of installation.

Avoid galvanized steel and PVC for hot drinking water, as they can pose health risks.