Note 13 - Segment Information - Summary of Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Revenue	$ 24,843	$ 25,858	$ 80,089	$ 100,160
Income (loss) from operations	369	(2,393)	(2,077)	5,938
Segment Reporting, Reconciling Item, Corporate Nonsegment [Member]
Revenue	82	74	238	223
Income (loss) from operations	411	(3,605)	(8,212)	(10,256)
Smart Water [Member] | Operating Segments [Member]
Revenue	10,518	9,913	27,278	20,558
Income (loss) from operations	2,233	2,611	4,023	5,372
Energy Solutions [Member] | Operating Segments [Member]
Revenue	8,107	9,382	34,977	60,328
Income (loss) from operations	(1,234)	(117)	5,380	13,003
Intelligent Industrial [Member] | Operating Segments [Member]
Revenue	6,136	6,489	17,596	19,051
Income (loss) from operations	$ (1,041)	$ (1,282)	$ (3,268)	$ (2,181)