Kirkland Signature vs Core Hydration: which water is healthier?

Updated October 7, 2026 · Scores from third-party lab reports · How we score

Kirkland Signature is the healthier choice, scoring 63/100 versus 50/100 for Core Hydration. The biggest differences are contaminants and PFAS testing.

Kirkland Signature

Kirkland Signature Purified Water Plastic Bottle

Core Hydration

Core Hydration Plastic Bottle

Side-by-side comparison

	Kirkland Signature	Core Hydration
Purity score	63/100	50/100
Product compared	Kirkland Signature Purified Water Plastic Bottle	Core Hydration Plastic Bottle
Type	Still	Still
Water source	Municipal Supply	Municipal Supply
Packaging	Plastic	Plastic
Microplastics risk	High	High
Lab tested	Yes	Yes
PFAS tested	Yes	No
Contaminants flagged	1	2
pH	5.9	7.4
TDS (minerals)	—	78 ppm
Fluoride	0 mg/L	0 mg/L

Score breakdown

Factor	Kirkland Signature	Core Hydration
Lab report indexed	45/45	45/45
Contaminants	17/50	0/50
Water source	15/25	15/25
Mineral preservation	17/17	17/17
Packaging material	2/22	2/22
Cap material	7/7	7/7
PFAS testing	5/5	0/5

Each brand is represented by its most popular product. See all products from Kirkland Signature and Core Hydration.

Frequently asked questions

Which is better, Kirkland Signature or Core Hydration?

Kirkland Signature is the healthier choice, scoring 63/100 versus 50/100 for Core Hydration. The biggest differences are contaminants and PFAS testing.

Is Kirkland Signature or Core Hydration better for avoiding microplastics?

Kirkland Signature (plastic) has a high microplastics risk and Core Hydration (plastic) has a high risk, based on packaging material.

Which has more minerals, Kirkland Signature or Core Hydration?

Total dissolved solids (TDS) is not reported for both products, so check each product page for its mineral list.