Tap Water in Cooking: The Ingredient We Never Question

Water is one of the most common ingredients in our kitchens.
It’s used to cook grains, boil vegetables, make soups, dilute sauces, brew tea and coffee, and prepare food for children.

Yet unlike every other ingredient, it’s rarely questioned.

Tap water is assumed to be neutral, safe by default, simply because it’s regulated. But regulation is not the same as health, and when it comes to cooking, this assumption deserves closer examination.

The Problem

Tap water is treated as a neutral cooking ingredient despite containing chemical disinfectants, heavy metals, and persistent environmental pollutants that remain — and can concentrate — during cooking.

Most water safety standards are designed to prevent acute toxicity, not long-term, cumulative exposure through food. They are also based on drinking water in isolation — not repeated daily use across meals, years, or decades.

Cooking changes the equation.

Why Cooking Changes Exposure

When water is heated, absorbed, or reduced, it doesn’t disappear — it becomes part of the food itself.

• Grains and legumes absorb water directly

• Pasta and vegetables trap it

• Soups, stocks, and sauces concentrate it

As water evaporates, anything dissolved in it remains behind. Cooking can therefore increase exposure density, not reduce it.

This matters because many of the most concerning compounds in tap water are not removed by heat.

What’s Commonly Found in Tap Water

Chlorine & Chloramine

Added to municipal water to control microbial growth.

• Stable under heat

• Can alter flavour and aroma

• Form disinfection byproducts when heated or combined with organic matter

These compounds were never intended to be consumed daily via food.

Heavy Metals (Lead, Copper, Arsenic)

Often introduced not at the treatment plant, but through household plumbing.

• Hot water increases metal leaching

• Older buildings are at higher risk

• Metals accumulate in the body over time

Using hot tap water for cooking — a common habit — can significantly increase exposure.

PFAS and Persistent Pollutants

Often referred to as “forever chemicals.”

• Resistant to heat and boiling

• Not removed through standard municipal treatment

• Bioaccumulative, meaning small exposures add up

These compounds are increasingly detected in public water supplies globally.

Why Taste and Clarity Don’t Indicate Safety

Many harmful contaminants are:

• Odorless

• Tasteless

• Invisible

Clear water is not clean water.
Compliance with legal thresholds does not equal biological neutrality.

The Overlooked Exposure Pathway: Food

Much of the conversation around water quality focuses on drinking. But for many people, food represents the larger exposure route.

If you cook at home regularly, tap water may be one of the most frequent chemical inputs in your diet — even if you never drink it directly.

Because it’s treated as infrastructure rather than an ingredient, it escapes scrutiny.

A More Intentional Approach to Cooking Water

This isn’t about fear.
It’s about alignment.

If you care about:

• Reducing cumulative toxic load

• Supporting gut and hormonal health

• Making informed, low-effort improvements

Then water deserves the same consideration as oils, produce, and sourcing.

Practical shifts

• Use filtered water for cooking, not just drinking

• Avoid using hot tap water entirely

• Be especially mindful with foods that absorb water (rice, grains, legumes)

• Treat water as a foundational ingredient, not a utility

Small changes, repeated daily, matter. When we pay attention to the ingredients we cook with most often, the quiet ones matter just as much as the obvious ones.

Resources & Further Reading

• World Health Organization — Guidelines for Drinking-Water Quality

• U.S. Environmental Protection Agency — Drinking Water Contaminants

• CDC — Lead in Drinking Water

• Peer-reviewed research on PFAS exposure and bioaccumulation

• Local municipal water quality reports (Consumer Confidence Reports)