How a Dialysis Machine Works, and What Happened to Dialysis in Gaza

A dialysis machine does part of the work of failed kidneys. It pumps a person's blood through a filter that removes waste, extra salt and extra water, then returns the cleaned blood to the body.

This guide explains how a hemodialysis machine works, how long treatment takes and what it needs to run, using information from the US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the National Kidney Foundation and the NHS. It then looks at what has happened to dialysis in Gaza, according to the World Health Organization (WHO). It is general information, not medical advice; a person's own kidney team decides their treatment.

What does a dialysis machine do?

Healthy kidneys filter the blood all day, removing waste and surplus water as urine. When they stop working properly, those wastes and fluids build up. The NHS describes dialysis as a procedure to remove waste products from the blood when the kidneys are not working properly.

There are two main kinds. In hemodialysis (spelled haemodialysis in British English), blood is cleaned outside the body by a machine. In peritoneal dialysis, a special fluid is run into the abdomen through a soft tube, where the lining of the abdomen acts as the filter; it is usually done at home every day. When people say "dialysis machine", they nearly always mean the hemodialysis machine, and that is what the rest of this guide describes.

How a hemodialysis machine works, step by step

The machine itself is mostly a pump and a set of safety monitors. The cleaning happens in the filter attached to it.

• Blood leaves the body. Soft tubes carry blood from the patient's access point (see below) to the machine, a little at a time.
• The pump moves it through the dialyzer. The dialyzer, sometimes called an artificial kidney, is the filter. Inside it, the National Kidney Foundation explains, blood flows on one side of a very thin membrane while dialysis fluid flows on the other.
• Waste crosses the membrane. Waste products such as urea and creatinine pass out of the blood into the dialysis fluid, while blood cells stay in the blood.
• Extra water is removed. The machine also draws off the fluid that failing kidneys can no longer remove.
• Clean blood returns. The filtered blood flows back to the body through a second tube, and the used fluid is discarded.

Dialysate: the fluid on the other side of the filter

The dialysis fluid is called dialysate. NIDDK describes it as water with chemicals added so that wastes, extra salt and fluid can be removed safely. A doctor can adjust the balance of chemicals in it according to a patient's blood tests and how they feel during treatment.

Throughout a session, NIDDK notes, the machine checks the patient's blood pressure and controls how quickly blood flows through the filter and how quickly fluid is removed.

This is why dialysis depends on more than the machine. Each session needs a filter, tubing, dialysate ingredients, a supply of treated water, and electricity for several hours.

Vascular access: how blood gets to the machine

Hemodialysis needs a reliable way to take blood out and return it, several times a week. NIDDK describes three types of access:

• An arteriovenous (AV) fistula, where a surgeon joins an artery to a vein, usually in the arm. NIDDK says it provides the highest blood flow and lasts longest. The NHS says it is usually made around 10 weeks before treatment starts.
• An AV graft, where a surgeon uses a man-made tube to connect an artery and a vein.
• A catheter, a tube placed in a large vein in the neck, chest or leg, generally used as a temporary access.

How long does dialysis take, and how often?

The standard schedule is three sessions a week of about four hours each. NIDDK gives that figure for treatment in a dialysis center, and the NHS says each session takes around four hours and most people need three a week. The National Kidney Foundation gives a range of three to five hours.

Some people have hemodialysis at home, which NIDDK says can mean three to seven sessions a week lasting between two and ten hours, depending on the plan.

Dialysis is not a cure. NIDDK is clear that hemodialysis replaces part, but not all, of what healthy kidneys do, and that it is a treatment for kidney failure, not a cure. Unless they receive a kidney transplant, people with kidney failure need dialysis for the rest of their lives. Shortened or missed sessions let waste and fluid build up again, which is why interruptions are so dangerous.

What happened to dialysis in Gaza

Before October 2023, Gaza had about 1,100 people on regular dialysis. WHO's situation updates still cite the Gaza Ministry of Health's estimate that up to 1,100 patients require regular hemodialysis.

By April 2025, the Associated Press reported, citing Gaza's Health Ministry, that more than 400 dialysis patients had died during the war for lack of proper treatment, around 40% of all cases. The same report cited WHO as saying six of Gaza's seven dialysis centers had been destroyed, and described patients receiving two shorter sessions a week in place of three.

WHO's update covering the period to 31 January 2026 gives the most detailed recent count. Four hospitals reported an estimated 641 patients receiving hemodialysis on 134 machines: Nasser Medical Complex, Al-Aqsa Hospital, Al-Zawaida Field Hospital and Al-Shifa Hospital. Eight deaths among hemodialysis patients were reported in December 2025 amid shortages of medicines and equipment, supplies of permanent dialysis catheters were critically low, and the Ministry of Health reported that 46% of the essential medicines for kidney transplantation and hemodialysis were at zero stock.

The shortages continued through 2026. In July, Al Jazeera reported the Ministry of Health as saying that half of Gaza's dialysis machines had stopped working because of a shortage of sodium bicarbonate, one of the ingredients of dialysate. On 24 September 2026, the WHO Director-General listed "people with kidney disease who cannot access regular dialysis" among the consequences of a health system in which only 19 of 36 hospitals were functioning even partially.

Why dialysis is so hard to keep going in a crisis

Few treatments are as exposed to a breakdown in basic services. A dialysis unit needs electricity for hours at a time, large volumes of clean treated water, a steady supply of filters, tubing and dialysate chemicals, working machines with spare parts, and patients who can physically reach it three times a week. In Gaza, fuel for hospital generators, clean water and medical supplies have all been short at once, and many patients have been displaced away from the units that treated them.

For some patients, the remaining option is treatment abroad; our guide to medical evacuations from Gaza explains how that works, and the Gaza hospitals guide tracks how many hospitals are functioning.

Fight for Palestine does not operate dialysis units or hospitals. We raise funds for emergency aid delivered through local partner teams, including medical aid; see our medical aid campaign.