What is the FAA law about restrooms ?

[Speedbird1]

After reading about the new longest flight, almost 19 hours from SIN to EWR, and with superb meal and beverage service, I was wondering about why the reporters aboard made no mention of bathroom use. Surely, there must be long lines for the few bathrooms available (only 6 on the new SIA A359 ULH). I have bladder problems as a senior and was just wondering. Are there guidelines by law?

[Landing Lights]

With only 159 seats onboard, 6 lavs is pretty generous. Compare that to the 3 (tiny) lavs for 172 seats on American Airlines 737MAX8. As for the volume of waste generated, I’m not intimately familiar with the details of the A350-900 ULR’s system, but I wouldn’t be surprised if the capacity is the same as a typical A350-900.