Dr Sarath Obeysekera 

AI generated advise 

For vegetables purchased in Sri Lanka, this is the household method I would recommend based on current research:

1. Remove damaged or outer leaves

For cabbage, lettuce, gotukola, spinach, mukunuwenna, etc., discard the outer leaves first.

2. Prepare a baking soda solution

• 1 teaspoon (about 5 g) of baking soda
• 2 cups (500 mL) of clean water
• Scale up as needed (e.g. 4 teaspoons in 2 litres of water).

3. Soak

• Soak vegetables for 10–15 minutes.
• Gently move them around during soaking.
• Research shows baking soda solutions generally remove more surface pesticide residue than plain water alone, although no method removes all residues, especially pesticides that have penetrated the produce. 

4. Rinse thoroughly

• Rinse under running filtered water for 30–60 seconds while rubbing the surface gently.

5. Dry

• Allow to drain or pat dry with a clean towel before storing or cooking.

For different vegetables

• Leafy vegetables: Separate the leaves before soaking.
• Tomatoes, cucumbers, brinjal: Rub gently while rinsing.
• Carrots, radish, potatoes: Use a clean vegetable brush under running water.
• Apples, grapes: The same baking soda method works well.

Avoid

• Soap or dishwashing liquid (these can leave residues that are not intended for consumption).
•  Strong bleach or disinfectants.
•  Assuming alkaline water (pH 9) alone is enough to remove pesticides. Current evidence does not support a meaningful advantage from alkaline water by itself over clean water; the main benefit comes from thorough washing, and baking soda can improve removal of some surface residues. 

Given the level of pesticide use on some vegetables in Sri Lanka, I also recommend:

• Buy seasonal produce whenever possible.
• Peel vegetables such as cucumbers, carrots, and potatoes if you are particularly concerned about residues.
• Cook vegetables thoroughly when appropriate, as cooking can further reduce residues of some pesticides. 

We worry about these issues when we get older 

My Alkaline water filter is effective to clean vegetables using water at Ph value 9

But Ai says otherwise 

• Filtered water is beneficial if your tap water contains chlorine, sediment, or other contaminants, but this benefit comes from the filtration, not from the higher pH.
• Alkaline water (pH 9) has not been shown in reliable scientific studies to remove significantly more pesticides than ordinary clean water.

Dr Sarath Obeysekera