Hydrotherapy Tubs: What Research Participants Actually Report vs What Marketing Promises

Marketing testimonials for hydrotherapy tubs follow a predictable pattern: a customer was in pain, bought the tub, and now feels wonderful. These stories are not necessarily false — but they are scientifically useless. Without a control group, blinding, or standardised measurement, a testimonial cannot tell you whether the tub caused the improvement, or whether time, placebo, seasonal change, or simply resting in warm water would have done the same.

This article does something different. Instead of collecting anecdotes, it examines what participants in controlled clinical trials actually report about hydrotherapy — their pain scores, satisfaction ratings, adherence over time, adverse events, and crucially, what happens when treatment stops. The picture that emerges is more nuanced than marketing suggests, but also more useful for anyone deciding whether a hydrotherapy tub is worth the investment.

Why Marketing Testimonials Are Not Evidence

Before examining the research, it is worth understanding why “customer reviews” for hydrotherapy products are unreliable as health evidence:

• Selection bias. People who had good experiences are more likely to leave reviews. Dissatisfied buyers often simply stop using the product and move on.
• No control group. A person who bought a hot tub and felt better cannot know whether they would have improved anyway. Many chronic pain conditions fluctuate naturally.
• Placebo effect. Spending £3,000–£8,000 on a wellness product creates strong expectation of benefit. Research consistently shows that more expensive placebos produce larger perceived effects.
• Regression to the mean. People tend to buy pain-relief products when their symptoms are at their worst. Symptoms often improve from their peak regardless of treatment.
• Undisclosed incentives. Some review sites offer discounts or affiliate commissions for positive reviews.

Clinical trials address these problems through randomisation, control groups, standardised outcome measures, and pre-registered protocols. They provide the closest thing we have to objective data on what hydrotherapy actually does.

What Clinical Trial Participants Report: Pain Outcomes

The largest relevant trial comparing aquatic therapy to standard treatment was published in JAMA Network Open by Peng et al. (2022). This single-blind randomised clinical trial enrolled 113 patients with chronic low back pain and followed them for 12 months.

Pain Reduction: Real but Modest

At 12-month follow-up, participants in the aquatic therapy group reported:

• Most severe pain: 53.6% achieved a clinically meaningful improvement, compared to 21.1% in the standard physical therapy group
• Current pain: 39.3% achieved meaningful improvement vs 17.5% in the control group
• Disability: 46.4% achieved meaningful improvement vs 7.0% in the control group

These are genuinely positive results — aquatic therapy outperformed standard physical therapy by a wide margin. But notice what the numbers also show: even in the aquatic therapy group, roughly half of participants did not achieve clinically meaningful pain improvement. Hydrotherapy helps many people, but it does not help everyone.

Quality of Life and Sleep

The same study found that aquatic therapy produced superior improvements in sleep quality and health-related quality of life (SF-36 scores) at 12 months. Anxiety and depression scores also improved more with aquatic therapy than with standard treatment.

A separate meta-analysis by Naumann and Sadaghiani (2014, Arthritis Research & Therapy) pooled 8 studies with 462 fibromyalgia patients and found a statistically significant but small improvement in both pain (SMD −0.42) and health-related quality of life (SMD −0.40). No significant effect was found for depressive symptoms or tender point count.

In plain language: hydrotherapy produces small, real improvements in pain and quality of life, particularly for chronic conditions. It does not eliminate pain, cure fibromyalgia, or produce the dramatic transformations described in marketing testimonials.

Patient Satisfaction: High — But With Caveats

In the Peng et al. (2022) trial, patient satisfaction was notably high:

• 92.9% of aquatic therapy participants said they would recommend the treatment to others
• This compared to 77.2% in the standard physical therapy group
• The difference was statistically significant (P = .01)

An NHS service evaluation by Pathak et al. (2025, Musculoskeletal Care) surveyed 69 patients who completed NHS-led hydrotherapy for persistent musculoskeletal pain. Patients rated perceived benefit at 7.7 out of 10 on average, with the highest ratings for ankle pain (9.8/10) and shoulder pain (9.0/10).

The high satisfaction is genuinely meaningful — people enjoy hydrotherapy and perceive real benefit. However, satisfaction and objective clinical improvement do not always align. The same NHS cohort showed an average MSK-HQ improvement of 5.2 points, which fell slightly below the 5.5-point threshold for clinically meaningful change. Patients felt better than the numbers strictly supported.

This is not necessarily a problem — if someone enjoys their hydrotherapy and feels it helps, that subjective benefit matters. But it is worth understanding when marketing uses “93% would recommend” as a proxy for “93% were cured.”

The Adherence Problem: What Happens When Treatment Stops

Perhaps the most important finding for anyone considering buying a hydrotherapy tub comes from what happens after formal treatment ends. The Pathak et al. (2025) NHS study tracked whether patients continued water-based exercise independently after their hydrotherapy sessions finished.

The results were sobering:

Self-Management Outcome	Number of Patients	Percentage
Maintained water-based exercise completely	15	22%
Maintained to some extent	5	7%
Did not maintain water-based exercise	49	71%

71% of patients stopped doing water-based exercise after NHS-led sessions ended. The barriers they reported were:

1. Need for ongoing support (15 patients) — “Four sessions was not enough”
2. Financial constraints (15 patients) — “I do not have the money” for pool access or home equipment
3. Access issues (11 patients) — “My pool is closed” or no local facilities
4. Insufficient improvement (6 patients) — The treatment did not help enough to motivate continued use

This has direct implications for anyone buying a home hydrotherapy tub: owning the equipment solves the access and cost-per-session problems but does not solve the motivation and support problems. If 71% of people stop water-based exercise even when they found it beneficial, a £5,000 tub in your garden may become an expensive garden ornament within months. The study authors specifically recommend peer support groups and structured ongoing guidance rather than assuming people will self-manage. For a realistic breakdown of what it costs to keep a home spa running, see our guide to running a hydrotherapy spa year-round in the UK.

Adverse Events: What Can Go Wrong

Marketing materials rarely mention risks. Clinical trials are required to report them. Here is what the evidence shows:

During Clinical Trials

Adverse event rates in hydrotherapy trials are consistently low. In the Peng et al. (2022) trial, only 1 participant out of 56 (1.8%) in the aquatic group reported intervention-related pain, compared to 2 out of 57 (3.5%) in the standard physical therapy group. Hydrotherapy was actually safer than the comparison treatment.

Hot Tub Folliculitis

The most common adverse event specific to hot tubs is Pseudomonas folliculitis — a bacterial skin infection caused by Pseudomonas aeruginosa. According to Jacob and Tschen (2020, Cureus), 67% of hot tubs and 63% of swimming pools test positive for this bacterium at any given time.

Symptoms appear 1–4 days after exposure as itchy red bumps, typically on areas covered by swimwear. Risk increases with longer immersion time, as water absorption through the skin’s outer layer (stratum corneum) increases with duration. The infection usually resolves on its own within 1–2 weeks without treatment.

Proper water maintenance (correct chlorine levels, regular filter cleaning, pH monitoring) substantially reduces this risk but does not eliminate it entirely.

Cardiovascular Risks

Water above 40°C can cause hypotension (low blood pressure), dizziness, and fainting, particularly in older adults or those on blood pressure medication. Šrámek et al. (2000, European Journal of Applied Physiology) showed that even thermoneutral water (32°C) reduces blood pressure by 11–12%. Hot water amplifies this effect. Anyone with cardiovascular conditions should consult their GP before using a hot tub regularly. To understand exactly why water temperature produces these effects, see our guide to the physics behind hydrotherapy machines.

The Expectations Gap: Marketing vs Measured Reality

What Marketing Says	What Research Shows
“Eliminates pain”	About half of participants achieve meaningful pain improvement; the other half do not (Peng et al., 2022)
“Transforms your wellbeing”	Small but statistically significant quality of life improvements (SMD −0.40) — real but modest (Naumann & Sadaghiani, 2014)
“Everyone loves it”	92.9% would recommend aquatic therapy — genuinely high satisfaction, though subjective benefit sometimes exceeds measured improvement
“Use it every day for best results”	71% of NHS hydrotherapy patients stopped independent water-based exercise after treatment ended (Pathak et al., 2025)
“Zero side effects”	1.8% reported intervention-related pain in trials; 67% of hot tubs harbour Pseudomonas bacteria; cardiovascular risks exist above 40°C
“Works for everyone”	Best evidence exists for chronic low back pain, fibromyalgia, and osteoarthritis; less evidence for other conditions
“Just relax and heal”	Passive soaking helps some measures, but active aquatic exercise consistently outperforms passive immersion in clinical outcomes

Who Benefits Most: What the Evidence Suggests

Based on the clinical trial data, certain groups consistently show the strongest outcomes from hydrotherapy:

• Chronic low back pain: The strongest evidence, with Peng et al. (2022) showing aquatic therapy superior to standard physical therapy at 12-month follow-up across pain, disability, sleep, and quality of life measures.
• Fibromyalgia: Consistent small benefits for pain and quality of life across multiple meta-analyses (Naumann & Sadaghiani, 2014 — 8 studies, 462 participants).
• Osteoarthritis: Buoyancy-driven joint offloading (up to 85% body weight reduction at shoulder depth) allows exercise that would be painful on land.
• Post-surgical rehabilitation: Reduced joint loading allows earlier return to movement after hip or knee replacement.
• People who enjoy water: The Pathak et al. (2025) study found that enjoyment was the strongest predictor of continued adherence. People who like being in water maintain the habit; those who are indifferent tend to stop.

Who May Not Benefit Enough to Justify the Cost

• People seeking passive pain relief only. The evidence is strongest for active aquatic exercise, not simply sitting in warm water. A tub used only for soaking provides thermal benefits but misses the movement-based outcomes that produce the best clinical results.
• People without a structured routine. The 71% dropout rate suggests that owning a tub without a plan for regular, structured use leads to abandonment. If you cannot commit to using it at least 2–3 times per week with purpose, the investment may not pay off.
• People with acute conditions. Hydrotherapy evidence is strongest for chronic conditions. Acute injuries may respond better to conventional physiotherapy or rest.
• People on very tight budgets. When the Pathak et al. study found cost was a top barrier, this reflected ongoing pool access costs. A home tub eliminates per-session fees but introduces maintenance, energy, and chemical costs (typically £50–£120 per month for a hot tub in the UK). A local pool session at £3–£6 per visit may be more cost-effective for most people.

Before You Buy: Questions the Research Suggests Asking

1. Will you use it actively or passively? If you plan to exercise in it, you need a swim spa or pool, not a hot tub. If you plan to soak, manage your expectations — thermal benefits are real but smaller than active exercise benefits.
2. Can you sustain 2–3 sessions per week long-term? The evidence base is built on regular use over months. Occasional use does not produce the outcomes seen in clinical trials.
3. Do you enjoy being in water? This sounds trivial but the research shows it is the strongest predictor of long-term adherence. Buying a tub because you think you should use it is different from buying one because you genuinely enjoy water immersion.
4. Have you tried pool-based hydrotherapy first? Before committing £3,000–£10,000 on home equipment, testing whether you respond well to water therapy through a few local pool or NHS-led sessions provides useful data at minimal cost. For help navigating the online marketplace, see our sceptical guide to buying hydrotherapy products online.
5. Can you maintain it? Water hygiene is non-negotiable. If the maintenance routine (testing chemicals, cleaning filters, monitoring temperature) feels burdensome, the tub will become a breeding ground for bacteria rather than a wellness tool.

For a structured decision framework that maps your specific therapeutic goal to the right equipment — with 5-year UK cost comparisons — see our evidence-based equipment guide.

Key Takeaways

• Hydrotherapy produces real, measurable benefits — but they are smaller than marketing suggests. About half of clinical trial participants achieve meaningful pain improvement; the other half do not (Peng et al., 2022, JAMA Network Open).
• Patient satisfaction is genuinely high — 92.9% would recommend aquatic therapy in the largest relevant trial, and NHS patients rated perceived benefit at 7.7/10 on average.
• The adherence problem is the biggest real-world challenge. 71% of NHS hydrotherapy patients stopped water-based exercise after treatment ended (Pathak et al., 2025). Owning a tub solves access but not motivation.
• Active use outperforms passive soaking in clinical outcomes. A tub used for structured exercise produces better results than one used only for relaxation.
• Adverse events are rare but real: 67% of hot tubs harbour Pseudomonas bacteria, water above 40°C carries cardiovascular risks, and proper maintenance is a safety requirement, not an optional extra.
• Try before you buy. A few pool-based or NHS hydrotherapy sessions can tell you whether you respond well to water therapy before committing thousands of pounds to home equipment. For a ranking of every hydrotherapy product category by research quality, see our evidence ranking guide.

Related Reading

• Hydrotherapy Equipment: An Evidence-Based Decision Framework
• How Hydrotherapy Machines Actually Work: The Physics Behind Every Claim
• Running a Hydrotherapy Spa Year-Round in the UK: Real Costs
• Buying Hydrotherapy Products Online: A Sceptical Guide

References

• Peng, M-S. et al. (2022). Efficacy of therapeutic aquatic exercise vs physical therapy modalities for patients with chronic low back pain. JAMA Network Open, 5(1), e2142069.
• Pathak, N. et al. (2025). Exploring barriers and facilitators to self-management for patients with persistent musculoskeletal conditions following NHS-led hydrotherapy. Musculoskeletal Care, 23(1), e70075.
• Naumann, J. & Sadaghiani, C. (2014). Therapeutic benefit of balneotherapy and hydrotherapy in the management of fibromyalgia syndrome: a qualitative systematic review and meta-analysis. Arthritis Research & Therapy, 16(4), R141.
• Jacob, J.S. & Tschen, J. (2020). Hot tub-associated Pseudomonas folliculitis: a case report and review of host risk factors. Cureus, 12(9), e10623.
• Šrámek, P. et al. (2000). Human physiological responses to immersion into water of different temperatures. European Journal of Applied Physiology, 81(5), 436–442.