With #1819 the state goes further away from 0 with time. That meanse we rely more on the relative tolerance than the aboslute tolerance.

Reducing the default `reltol` by two orders of magnitude is enough to get only negligible leaky Terminals with occasional very brief leaks of 1e-8 m3/s. It is also enough to minimize the infiltration error to acceptable levels as can be seen in #1863 (comment).

For HWS this slows down simulation from 9.1s to 12.3s, which isn't too bad for a two orders of magnitude reduction in relative tolerance.

https://docs.sciml.ai/DiffEqDocs/stable/basics/faq/#What-does-tolerance-mean-and-how-much-error-should-I-expect