pH Test Results


  • Most of the things we tested were around ph 6 or 7 (i.e. Neutral).
  • We found a general trend for nappies to become more alkaline (pH greater than 7), the longer they were in the dry pail. We know that alkaline conditions promote the formation of Hydroxl Apatite (HA), so perhaps HA is forming in the bucket, before the nappies are washed?

NB: The inaccuracy of pH papers means that a pH of 6 or 7 should be considered neutral

Result 1: Most people found that their tap water was neutral (pH 6 or 7)

(I am a little concerned about the person who found their tap water was pH 4 – this test should be repeated and if necessary investigated by a professional plumber)


Result 2: There was a general trend for night nappies to become more alkaline (pH greater than 7) the longer they were left in the dry pail.

The experts have told us that alkaline conditions promote the formation of Hydroxl Apatite (HA), so perhaps HA is forming in the bucket, before the nappies are washed? (as suggested during the live chat with Elaine and Greg)

There seemed to be a general trend towards the nappies becoming more alkaline after spending some time in the dry pail, so I looked closer at the data.
For the graph below, I subtracted the original pH (upon removal from bum) from final pH (after dry pailing) and plotted this against hours spent in bucket (eg pH of 7 when removed from bum, followed by a pH of 9 after dry pailing, would be a pH change of 9 – 7 = 2).  I then asked Excel to add a trendline (dotted line on graph).

We hypothesize that the increase in pH that we have observed is due to urea being converted to ammonia. Urea is the waste product from our normal body processes which the body flushes out as urine. Urea is neutral (pH 7), but once it is out of the body, it is converted to ammonia by natural bacteria. Ammonia is responsible for the nasty ‘urine’ smell in some public toilets!


Here is a closer look at some of the data where people saw a decrease in pH (-1 or -2 on the above graph). Can anyone spot any trends or possible reasons why these particular nappies may be different?

Diet pH of night nappy upon removal pH after dry pailing Any other notes
Breast milk, solids, Vegetarian, 8.5 7.5  (3 days) 8 hours on top of pile in a lidded (not air tight) bucket, from wee zone that was cl
Solids 8 6 (1 day)
Solids 7 6 (36 hrs)
Solids, Dairy and soya free 8 7 (12 hrs) Teething
Breastmilk and solids 10 9 (1 day)
For comparison – the other special diet results


Solids, Dairy free 6.5 8 (3 days) 3 days in warm bathroom
Solids, Dairy free (except milk cooked for a long time, stage 4 milk ladder) 6 7 (12 hrs) I also did a test on the previous night’s cotton nappy, which came out at pH 8 (36 hrs in pail)

Result 3: Nappies and clothes straight out the washing machine were largely neutral (pH 6 or 7).

These results were almost identical to those found for tap water (see graph above) as would be expected for well rinsed items.

Result 4: Most people found that their toddler urine was neutral (pH 6 or 7).

However, we did get one acidic result (pH 5) with the notes “She is teething. It was first thing in the morning.”

And two alkaline results (pH 8) with the comments “Light urine” and “Light, well hydrated in colour” (although most of the pH 6 and 7 results also commented the urine was light in colour).

This test also generated several amusing comments such as:

“Couldn’t see colour, wee was tested from the carpet …!”

“She weed immediately after getting off the potty (typical!) so I didn’t see the colour but got it from the changing mat.”


Thank you to all the volunteers who took part in this experiment and took the time to complete the survey.


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