Every ASX dividend share offers something different, and a few have virtually unique qualities.

Being unique doesn't necessarily mean it's a great investment. However, if it offers regular dividend growth, it could be a particularly attractive business to own.

Over the last few years, we've seen how inflation can be a dangerous financial force, eating away at the value of a dollar. For that reason, I believe dividend growth is an important attribute.

The two ASX dividend shares below offer both dividend growth and something unique, in my opinion.

Duxton Water Ltd (ASX: D2O)

This company has built a portfolio of permanent water entitlements and uses this to provide farmers with flexible water supply. Irrigators can utilise long-term entitlement leases, forward allocation contracts and spot allocation supply.

Pleasingly, the business has grown its payout every six months since 2017, which is an impressively long record considering how many other companies have cut their payouts during that time.

Duxton Water said in its June monthly update that the past 12 months have been significantly drier, resulting in increased demand for long-term water security. As of 30 June 2025, the major southern Murray-Darling Basin storages were at their lowest levels in five years for this time of the year, contributing to a reduced supply of available water, according to Duxton Water.

Market prices of high-security entitlement leases have increased over the last three or four months, reflecting stronger demand.

The ASX dividend share trading at a 9% discount to the post-tax net asset value (NAV), enabling it to provide a solid trailing grossed-up dividend yield of 7%, including franking credits.

Washington H. Soul Pattinson and Co. Ltd (ASX: SOL)

Soul Patts is one of the oldest businesses on the ASX. It's over 120 years old and has been listed during all of that time.

One of the most important things that dividend investors need to know about this company is that it has paid a dividend in every one of those 120+ years, and it has also grown its annual ordinary dividend every year since 2000.

This ASX dividend share is virtually unique because it owns an extensive portfolio of private and public investments. Some of its private businesses include electrification, swimming schools, agriculture, financial services, and credit.

It also owns numerous ASX shares in its portfolio, including Brickworks Ltd (ASX: BKW), New Hope Corporation Ltd (ASX: NHC), TPG Telecom Ltd (ASX: TPG), Tuas Ltd (ASX: TUA), Perpetual Ltd (ASX: PPT), BHP Group Ltd (ASX: BHP), Macquarie Group Ltd (ASX: MQG), Wesfarmers Ltd (ASX: WES), Commonwealth Bank of Australia (ASX: CBA), and Goodman Group (ASX: GMG).

Not only does it have an incredible track record of dividend reliability, but it also has a pleasingly diverse portfolio, as I've outlined above. Its grossed-up dividend yield is 3.4%, including franking credits.