Note 2 - Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Total revenue	$ 24,843	$ 25,858	$ 80,089	$ 100,160
Product [Member]
Total revenue	23,227	20,223	74,580	83,434
Operating Segments [Member] | Smart Water [Member]
Total revenue	10,518	9,913	27,278	20,558
Operating Segments [Member] | Smart Water [Member] | Product [Member]
Total revenue	10,518	9,913	27,278	20,558
Operating Segments [Member] | Energy Solutions [Member]
Total revenue	8,107	9,382	34,977	60,328
Operating Segments [Member] | Energy Solutions [Member] | Product [Member]
Total revenue	6,612	3,862	29,837	43,948
Operating Segments [Member] | Intelligent Industrial [Member]
Total revenue	6,136	6,489	17,596	19,051
Operating Segments [Member] | Intelligent Industrial [Member] | Product [Member]
Total revenue	$ 6,097	$ 6,448	$ 17,465	$ 18,928