Note 2 - Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Total revenue	$ 15,804	$ 24,843	$ 61,132	$ 80,089
Product [Member]
Total revenue	15,218	23,227	58,571	74,580
Operating Segments [Member] \| Smart Water [Member]
Total revenue	4,622	10,518	14,106	27,278
Operating Segments [Member] \| Smart Water [Member] \| Product [Member]
Total revenue	4,622	10,518	14,106	27,278
Operating Segments [Member] \| Energy Solutions [Member]
Total revenue	5,851	8,107	30,116	34,977
Operating Segments [Member] \| Energy Solutions [Member] \| Product [Member]
Total revenue	5,387	6,612	27,937	29,837
Operating Segments [Member] \| Intelligent Industrial [Member]
Total revenue	5,246	6,136	16,656	17,596
Operating Segments [Member] \| Intelligent Industrial [Member] \| Product [Member]
Total revenue	$ 5,209	$ 6,097	$ 16,528	$ 17,465

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details