Parents in Wales owed more than £400,000 in unpaid school dinner debts at the end of last year, figures have shown.
In seven Welsh authorities, the debt has leapt by nearly 90% in the space of five years.
Rowan Davies, of website Mumsnet, said schools should offer "flexibility" to avoid parents feeling "embarrassed".
The Welsh Local Government Association has been asked to comment.
Last month, Denbighshire Council defended its policy on dinner debts, after a single mother said she was threatened with referral to social services when she was late paying a £13 bill.
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Damien Challenger has witnessed it from both sides of the table - as one the people behind the teaching network Nexus Education - and as parent.
As a parent, he received a text over a £2 debt for a meal.
"I think sometimes the language used in these texts to parents can be quite abrasive and it puts a parent on the defensive rather than wanting to communicate with the school they might have issues," he said.
Councils have different policies on how long a child will be allowed to accrue debts before lunch is withheld, what alternative is offered and how debts are recovered.
In many cases, the action taken is up to individual schools, with debts over a certain size transferred to their local authority to recover.
In Wrexham's primary schools pupils are allowed a five-day overdraft facility before they are refused a meal, with debts over £25 referred to debt collectors. In Carmarthenshire, the limit is £30, with reminders being sent and it is £50 in Conwy.
Council debts for 2017/18
- Blaenau Gwent: £5,771.94
- Carmarthenshire £61,011
- Ceredigion: £38, 190.46
- Cardiff City: £9,000.78
- Conwy: £26,192.20
- Denbighshire: £46, 731.27
- Gwynedd: £85,589.47
- Merthyr Tydfil £46,575. 48
- Monmouthshire: £11,052
- Newport: £17, 171
- Powys: £46,164.55
- Rhondda Cynon Taf: £770.56
- Swansea: £18,600
- Torfaen: £47,812.6
As of March 2017-18
Hot meals are "stopped" in Denbighshire after a debt reaches £20, with children offered a sandwich and a cold drink instead.
In Pembrokeshire, there is no limit to the number of meals a child can receive while in arrears, although debts there will be passed on to collectors after a month without payment.
The highest debts were recorded by Gwynedd - with one school alone topping £18,000.
The council said schools sent out two reminders in the month if parents provide no explanation for non-payment, then the debt is transferred to the council and the families are invoiced within 28 days.
Rowan Davies, head of policy and campaigns at Mumsnet, said: "I think flexibility around cash payments [would be helpful].
"There might be times of the month where parents are able to pay for school dinners, there might be times where they need to switch to packed lunches.
"Something a lot of parents find difficult is going to the school secretary. You don't necessarily want to go and tell that person you're struggling with money."
Online and banking payment systems are in place or being rolled out across most of Wales, eliminating the need for children to bring cash into school.
The ParentPay system is used at Osbaston Church in Wales Primary School in Monmouth, means "less chasing" for debt head teacher Catherine Jones said.
"We would always be there to support; we would never at any point deny a child a school meal," she added.