Quick Answer: On The Go is the brand behind the two most-recommended portable water softeners on the market — the OTG4-DBLSOFT (16,000 grain, double-tank, roughly $225-$260) and the smaller OTG4-StdSoft (8,000 grain, single-tank, roughly $170-$210). Both use the same brass fittings, food-grade resin, and manual table-salt regeneration; the only real difference is how many gallons you get between refills. Neither model uses electricity, a timer, or a drain line — you regenerate by hand in under 30 minutes, which is the entire appeal for RVs, boats, and apartments where permanent plumbing isn’t an option.
On The Go has been the default name in the portable-softener category for long enough that it shows up as the top pick in nearly every third-party RV and apartment-softener comparison, and it’s the brand our own best portable water softener roundup names as the overall winner. That guide compares On The Go against three competing brands; this review goes deeper on On The Go’s own lineup specifically — which of its two models actually fits your situation, and where the brand’s approach falls short of a whole-house system.
On The Go lineup at a glance
| Model | Best for | Capacity | Tanks | Price |
|---|---|---|---|---|
| On The Go OTG4-DBLSOFT | Best overall / longest runway | 16,000 grain | 2 (double) | ~$225-$260 |
| On The Go OTG4-StdSoft | Best compact / budget | 8,000 grain | 1 (single) | ~$170-$210 |
1. On The Go OTG4-DBLSOFT — Best Overall
On The Go OTG4-DBLSOFT 16,000 Grain Double Tank
- Two 8,000-grain resin tanks plumbed in series for a combined 16,000 grains — roughly 1,000-1,600 gallons of soft water per fill depending on incoming hardness.
- Brass, drinking-water-safe fittings connect straight to a garden hose or washing-machine bib with no tools.
- Regenerates with two boxes of ordinary table salt in under 30 minutes, no electricity or drain line required.
Softener salt and resin on time, every time — Amazon Prime ships them free in two days, and you can try it free for 30 days.
The double-tank design is what separates the DBLSOFT from most of its budget competitors, which typically ship as a single 16,000-grain tank instead of two 8,000-grain tanks in series. In practice that means slightly more consistent output as the resin bed depletes, since water passes through two beds instead of exhausting one — a small but real edge for anyone running a full RV trip or a multi-week apartment stretch between regenerations. According to the U.S. Geological Survey, water above roughly 180 mg/L (about 10.5 grains per gallon) is classified as “very hard” — at that hardness level, the DBLSOFT’s extra capacity over the single-tank model buys meaningfully more days before you’re regenerating again.
2. On The Go OTG4-StdSoft — Best Compact / Budget
On The Go OTG4-StdSoft 8,000 Grain Single Tank
- Single tank at roughly half the size and weight of the DBLSOFT — easier to store in an apartment closet, RV basement bay, or boat locker.
- Same brass fittings, food-grade resin, and no-tools garden-hose connection as the double-tank model.
- Lower upfront cost for one or two people, or intermittent use, where 16,000 grains of runway goes unused between trips.
The StdSoft isn’t a stripped-down version of the DBLSOFT so much as a genuinely smaller unit for a genuinely smaller use case — solo travelers, weekend-only cabins, or apartment renters who’d rather regenerate more often than store a bigger tank. You’ll refill salt roughly twice as often for the same water usage, which is a fair trade if storage space or upfront cost matters more than runway.
Where On The Go actually fits
Both models share the same core mechanism as a whole-house softener — ion-exchange resin swapping calcium and magnesium for sodium — just shrunk into a hose-fed tank you regenerate by hand instead of a plumbed-in cabinet that regenerates itself on a timer or meter. That tradeoff is the entire pitch: zero installation, no drain line, no landlord approval, and nothing electronic to fail. It’s the right call for RVs, boats, apartments, and rentals. It’s the wrong call for a house you own with normal daily water usage, where the constant hand-regeneration would get old fast and a plumbed-in system pays for itself in convenience alone — see our best water softener pillar or sizing guide for that comparison.
On The Go vs. the rest of the portable-softener field
Our best portable water softener roundup also covers VEVOR’s 16,000-grain unit (similar capacity, lower price, shorter track record) and Mobile-Soft-Water’s fiberglass-tank model (higher flow rate, roughly $300-$360, built for full-time RVers running the softener hard). On The Go sits in between on price and holds the edge on being the name that shows up most consistently across independent reviews — worth the premium over VEVOR if brand track record matters more to you than shaving $50-100 off the purchase price.
The bottom line
The OTG4-DBLSOFT is the right default On The Go pick for most RV, boat, and apartment use — 16,000 grains and double-tank capacity cover a full trip or several weeks without a refill. Go with the smaller OTG4-StdSoft if you’re a solo or occasional user who’d rather save on price and storage space than maximize runway. Either way, you’re regenerating by hand with ordinary table salt — our best water softener salt guide covers which salt type works best for that. If you’re softening a fixed home instead of a moving RV or a rental, our best portable water softener roundup and best water softener pillar both cover the alternatives worth comparing against.