Document and Entity Information - shares	3 Months Ended
	Dec. 31, 2020	Jan. 25, 2021
Entity Registrant Name	OneWater Marine Inc.
Entity Central Index Key	0001772921
Current Fiscal Year End Date	--09-30
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity Address, State or Province	GA
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Common Class A [Member]
Entity Common Stock, Shares Outstanding		10,867,291
Common Class B [Member]
Entity Common Stock, Shares Outstanding		4,108,007